synthesis of lipid based polyols from 1-butene ...343... · oil for use in polyurethane foam...

Synthesis of Lipid Based Polyols from 1-butene Metathesized

Palm Oil for Use in Polyurethane Foam Applications

A Thesis Submitted to the Committee on Graduate Studies

in Partial Fulfillment of the Requirements for the Doctor of Philosophy in the Faculty

of Arts and Science

TRENT UNIVERSITY

Peterborough, Ontario, Canada

© Copyright by Prasanth Kumar Sasidharan Pillai 2015

Materials Science PhD. Graduate Program

January 2016

ii

Abstract

Synthesis of Lipid Based Polyols from 1-Butene Metathesized Palm

Oil for Use in Polyurethane Foam Applications

Prasanth Kumar Sasidharan Pillai

This thesis explores the use of 1-butene cross metathesized palm oil (PMTAG) as a

feedstock for preparation of polyols which can be used to prepare rigid and flexible

polyurethane foams. PMTAG is advantageous over its precursor feedstock, palm oil, for

synthesizing polyols, especially for the preparation of rigid foams, because of the reduction

of dangling chain effects associated with the omega unsaturated fatty acids. 1-butene cross

metathesis results in shortening of the unsaturated fatty acid moieties, with approximately

half of the unsaturated fatty acids assuming terminal double bonds. It was shown that the

associated terminal OH groups introduced through epoxidation and hydroxylation result in

rigid foams with a compressive strength approximately 2.5 times higher than that of rigid

foams from palm and soybean oil polyols. Up to 1.5 times improvement in the compressive

strength value of the rigid foams from the PMTAG polyol was further obtained following dry

and/or solvent assisted fractionation of PMTAG in order to reduce the dangling chain effects

associated with the saturated components of the PMTAG. Flexible foams with excellent

recovery was achieved from the polyols of PMTAG and the high olein fraction of PMTAG

indicating that these bio-derived polyurethane foams may be suitable for flexible foam

applications. PMTAG polyols with controlled OH values prepared via an optimized green

solvent free synthetic strategy provided flexible foams with lower compressive strength and

iii

higher recovery; i.e., better flexible foam potential compared to the PMTAG derived foams

with non-controlled OH values. Overall, this study has revealed that the dangling chain issues

of vegetable oils can be addressed in part using appropriate chemical and physical

modification techniques such as cross metathesis and fractionation, respectively. In fact, the

rigidity and the compressive strength of the polyurethane foams were in very close agreement

with the percentage of terminal hydroxyl and OH value of the polyol. The results obtained

from the study can be used to convert PMTAG like materials into industrially valuable

materials.

Keywords

Cross Metathesis; Metathesized Triacylglycerol (MTAG); Fractionation; Polyols;

Hexol; Tetrol; Diol; Olein; Stearin; Glycerol Composition; Polyurethane Foams;

Compressive Strength; Recovery.

iv

Acknowledgements

Its extreme pleasure to thank all the good hearted people who showered immense

support and help in achieving this milestone. I would never be able to finish this Ph.D without

the kind contributions from many of the wonderful people. In this pleasant occasion I would

like to thank all these wonderful people from my heart.

I would like to express my sincere thanks and respect to my supervisor, Prof. Suresh S.

Narine for giving me this wonderful opportunity. At this time I thank him for his magnificent

guidance and immense support throughout the program. He is a brilliant mentor as well as a

good friend who cares a lot about the welfare of the people who depended on him. Without

the priceless learning and incalculable experience obtained from him, I would not be able to

finish this work. I would like to thank Dr. Laziz Bouzidi and Dr. Shaojun Li for their kind

advices and valuable suggestions during my Ph.D. Also I take this opportunity to thank my

supervisory committee members Dr. Andrew Vreugdenhil and Dr. Ghaus Rizvi for their kind

advices and motivations.

I would like to thank Professor Sabu Thomas for their immense and generous help

showered one me on all my difficult times. I am also Thankful to Dr. Laly A. Pothen and

Abraham Mathew for their immense support and motivation all the time.

I have a million thanks for Ms. Athira Mohanan for her incredible and selfless support

throughout the Ph.D. Without her unconditional support and valuable advices, I would not be

able to finish my Ph.D.

I am thanking all my colleagues Ms. Latchmi Regunanan, Ms. Shegufa Merchant, Mr.

Michael Floros, Mr. Avinaash Persaud and Dr. Jesmy Jose for their kind help and valuable

v

suggestions throughout my Ph.D. Also I am grateful to our Lab managers and technicians Ali

Mahdevari, Carolyn Payne, John Breukelar, Peter Andreas for their valuable supervision and

support during this period. I would like to thank Rekha Singh, the administrative secretary of

our group for her kind support on all difficult times during my Ph.D.

I would like to thank the Grain Farmers of Ontario, Elevance Renewable Sciences, Trent

University, the GPA-EDC, Ontario Ministry of Agriculture, Food and Rural Affairs, Industry

Canada and NSERC for their financial support

I thank all my friends for their valuable suggestions throughout my life. A special thanks

to Mr. Tino Justin, Hassan Damji, Mohammed Jawad Nathoo and Mike Harrison Charles,

who were always there with me on all my difficulties. I am also grateful to Dr. Swaroop

Sasidharan Pillai, Dr. Dinesh T. Sreedharan for their precious support.

Finally my appreciation goes to my family for their selfless support. Exclusively, I am

always grateful to my parents, Sasidharan Pillai and Prasanna Kumari. I would like to thank

my sister Sree Lekshmi. P and brother in law Sarath S. Kurup for their unconditional support

and taking care my parents Sasidharan Pillai and Prasanna Kumari while I am miles away

from home. Also I am so thankful to my uncle B. Sivan Pillai for his support and advices

throughout my life.

vi

Table of Contents

Abstract ........................................................................................................................... ii

Keywords ...................................................................................................................... iii

Acknowledgements ....................................................................................................... iv

Table of Contents .......................................................................................................... vi

List of Figures ............................................................................................................... xii

List of Schemes ........................................................................................................... xvi

List of Tables ............................................................................................................... xix

List of Abbreviations ................................................................................................ xxiii

1 Introduction............................................................................................................ 1

1.1 Motivation and Objectives .................................................................................... 1

1.2 Background ........................................................................................................... 4

1.2.1 Polyurethanes ............................................................................................... 4

1.2.2 Polyurethane foams ..................................................................................... 5

1.2.3 Polyols ......................................................................................................... 6

1.2.4 Petroleum Polyols ........................................................................................ 6

1.2.5 Vegetable Oil Based Polyols ....................................................................... 8

1.3 Factors Determining the Properties of PU Foams............................................... 14

1.3.1 Effect of Polyol Structure .......................................................................... 14

1.3.2 Effect of Isocyanate ................................................................................... 15

1.3.3 Effect of Catalyst ....................................................................................... 16

1.3.4 Effect of Blowing Agent ............................................................................ 17

1.3.5 Effect of Surfactant .................................................................................... 18

1.4 Problems of Vegetable oil Derived PU Foams ................................................... 19

vii

1.5 Rectification of Dangling Chain Issue ................................................................ 19

1.5.1 Olefin Metathesis ....................................................................................... 19

1.5.2 Fractionation by Crystallization ................................................................ 22

1.6 Hypotheses .......................................................................................................... 23

1.7 Thesis Outline ..................................................................................................... 26

1.8 References ........................................................................................................... 27

2 1-Butene Metathesized Palm Oil & Polyol Derivatives: Structure, Chemical

Composition and Physical Properties.................................................................. 43

2.1 Introduction ......................................................................................................... 43

2.2 Materials and Methods ........................................................................................ 49

2.2.1 Materials .................................................................................................... 49

2.2.2 Chemistry characterization techniques ...................................................... 49

2.2.3 Physical characterization techniques ......................................................... 52

2.3 Results and Discussion ........................................................................................ 54

2.3.1 Chemical Characterization of PMTAG ..................................................... 54

2.3.2 Compositional Analysis of PMTAG ......................................................... 55

2.3.3 Physical Properties of PMTAG ................................................................. 62

2.3.4 Synthesis of PMTAG Polyol ..................................................................... 68

2.3.5 Compositional analysis of PMTAG Polyol ............................................... 75

2.3.6 Composition of PMTAG Polyol ................................................................ 81

2.3.7 Physical Properties of PMTAG Polyol ...................................................... 82

2.4 Conclusions ......................................................................................................... 88

2.5 References ........................................................................................................... 90

viii

3 Water-Blown Bio-Based Rigid and Flexible Polyurethane Foams from 1-Butene

Metathesized Palm oil Polyol ............................................................................. 96

3.1 Introduction ......................................................................................................... 96

3.2 Materials and Methods ...................................................................................... 100

3.2.1 Materials .................................................................................................. 100

3.2.2 Polymerization Method ........................................................................... 101

3.2.3 Chemistry and Physical characterization techniques ............................... 101

3.2.4 Preparation of PU rigid and flexible foams ............................................. 103

3.3 Results and discussion ...................................................................................... 106

3.3.1 FTIR Characterization of Foams ............................................................. 106

3.3.2 SEM analysis of PMTAG Polyol Foams ................................................. 107

3.3.3 Thermal Stability of Foams ..................................................................... 109

3.3.4 DSC of Rigid and Flexible Foams ........................................................... 110

3.3.5 Compressive Strength of PMTAG Polyol Foams ................................... 112

3.3.6 Recovery of Flexible Foams .................................................................... 115

3.4 Conclusions ....................................................................................................... 117

3.5 References ......................................................................................................... 118

4 Fractionation Strategies for Improving Functional Properties of Polyols and

derived Polyurethane Foams from 1-butene Metathesized Palm Oil................ 122

4.1 Introduction ....................................................................................................... 122


4.2.1 Materials .................................................................................................. 125

4.3 Chemistry Characterization Techniques ........................................................... 126

4.3.1 Titrimetric Methods (OH value, Acid value, Iodine value) .................... 126

ix

4.3.2 Proton Nuclear Magnetic Resonance Spectroscopy (1HNMR) ............... 126

4.3.3 Fourier Transform Infrared Spectroscopy (FTIR) ................................... 126

4.4 Physical Characterization Techniques .............................................................. 126

4.4.1 Thermogravimetric Analysis (TGA) ....................................................... 126

4.4.2 Differential Scanning Calorimetry (DSC) ............................................... 127

4.4.3 Rheology .................................................................................................. 128

4.4.4 Scanning Electron Microscopy (SEM) .................................................... 129

4.4.5 Compressive Strength .............................................................................. 129

4.5 Fractionation of PMTAG by dry and solvent mediated crystallization ............ 129

4.5.1 Dry crystallization experiments ............................................................... 131

4.5.2 Solvent Mediated Crystallization Experiment ......................................... 132

4.6 Synthesis of the Polyols .................................................................................... 133

4.6.1 Epoxidation .............................................................................................. 134

4.6.2 Hydroxylation .......................................................................................... 134

4.7 Polymerization Method ..................................................................................... 135

4.8 Results and Discussion ...................................................................................... 136

4.8.1 Results of the fractionation of PMTAG .................................................. 136

4.8.2 1H-NMR Characterization of the PMTAG fractions ............................... 138

4.8.3 Characterization of the polyols synthesized from LF- and SF-PMTAG . 140

4.8.4 Crystallization and Melting Behavior of LF- and SF- Polyols ................ 142

4.8.5 Flow Behavior and Viscosity of LF- and SF-PMTAG Polyols ............... 144

x

4.9 Polyurethane Rigid and Flexible Foams ........................................................... 145

4.9.1 FTIR of LF-PMTAG Polyol Foams ........................................................ 146

4.9.2 SEM Analysis of LF-Polyol Foams ......................................................... 147

4.9.3 Thermal degradation Properties of LF-Polyol Foams ............................. 148

4.9.1 Thermal transition Properties of LF-Polyol Foams ................................. 150

4.9.2 Compressive Strength of LF-Polyol Foams ............................................ 150

4.10 Conclusions ....................................................................................................... 153

4.11 References ......................................................................................................... 155

5 Solvent Free Synthesis of Polyols From 1- Butene Metathesized Palm Oil for

Use in Polyurethane foams ............................................................................... 158

5.1 Introduction ....................................................................................................... 158


5.2.1 Materials .................................................................................................. 161

5.2.2 Chemistry Characterization ..................................................................... 161

5.2.3 Physical Characterization Techniques ..................................................... 163

5.2.4 Synthesis Methods ................................................................................... 165

5.3 Results and Discussion ...................................................................................... 169

5.3.1 Solvent Free Synthesis of Polyol from PMTAG ..................................... 169

5.3.2 Chemical Characterization and Compositional Analysis of PMTAG Green

Polyols ..................................................................................................... 170

5.3.3 Physical Properties of PMTAG Green Polyols ....................................... 175

5.3.4 Polyurethane Foams ................................................................................ 180

xi

5.4 Conclusions ....................................................................................................... 191

5.5 References ......................................................................................................... 193

6 Conclusion ......................................................................................................... 197

6.1 General Conclusion ........................................................................................... 197

6.2 Rigid foams from PMTAG ............................................................................... 197

6.3 Flexible foams from PMTAG ........................................................................... 198

6.4 Foams from fractionated PMTAG .................................................................... 199

6.5 Green Polyols and Foams ................................................................................. 200

6.6 Summary ........................................................................................................... 200

6.7 Implications of this study .................................................................................. 201

6.8 Future Prospects ................................................................................................ 201

Appendix .................................................................................................................... 204

A1 Butene Cross metathesized Palm oil and Polyol Derivatives: Structure and

Physical properties ............................................................................................ 204

A2 Fractionation Strategies for Improving Functional Properties of Polyols and

derived Polyurethane Foams from 1-butene Metathesized Palm Oil................ 213

A3 Solvent Free Synthesis of Polyols from 1-Butene Metathesized Palm Oil for Use

of Polyurethane Foams ...................................................................................... 224

xii

List of Figures

Figure 2.1. 1H-NMR of PMTAG. (a) Chemical shift range between δ 2.5 and 0.7 ppm, (b)

Chemical shift range between δ 6.0 and 4.0 ppm .................................................................. 58

Figure 2.2. HPLC of PMTAG (solid line) superimposed with the HPLC of DDD, DDS and

DSS. The standard TAGs are indicated at the side of their HPLC trace (dashed lines) ........ 60

Figure 2.3: TGA and DTG profiles of the PMTAG.............................................................. 63

Figure 2.4: (a) Crystallization thermograms of PMTAG obtained (b) corresponding heating

profiles (both at 5 °C/min) ..................................................................................................... 64

Figure 2.5: Shear rate versus shear stress of the PMTAG .................................................... 67

Figure 2.6: Viscosity versus temperature of PMTAG. Dotted lines are fit to the generalized

van Velzen equation (eq.2). The lower panel represents the residuals in % (RD%) versus

temperature. ........................................................................................................................... 68

Figure 2.7. 1H-NMR spectrum of epoxy PMTAG ................................................................ 71

Figure 2.8. 1H-NMR of (a) PMTAG Polyol H1and (b) PMTAG Polyol H2 and H3 ........... 73

Figure 2.9. HPLC of PMTAG Polyol. .................................................................................. 79

Figure 2.10: TGA and DTG profiles of PMTAG Polyol. ..................................................... 83

Figure 2.11: (a) Crystallization of PMTAG polyol (b) heating profile of PMTAG polyol. . 84

Figure 2.12: Shear rate versus shear stress of PMTAG Polyol ............................................. 86

Figure 2.13: Viscosity versus temperature measured while cooling PMTAG Polyol at () 1

°C/min. Dotted lines represent the calculated viscosity using the generalized van Velzen

equation (Eq.2.2). Lower panel represent the residuals in % (RD%) versus temperature. The

cut-off is indicated with a vertical dashed line. ..................................................................... 87

xiii

Figure 3.1: Pictures of (a) Rigid PMTAG Polyol Foam, and (b) Flexible PMTAG Polyol

Foam .................................................................................................................................... 106

Figure 3.2. Typical FTIR spectra of the PMTAG Polyol foams. (1) PMTAG Polyol Rigid

Foam and (2) PMTAG Polyol Flexible Foam ..................................................................... 107

Figure 3.3. Typical SEM micrographs of (a) Rigid PMTAG Polyol foams and (b) Flexible

PMTAG Polyol Foam .......................................................................................................... 108

Figure 3.4: TGA and DTG profiles of (a) PMTAG rigid foam and (b) PMTAG flexible foam.

.............................................................................................................................................. 109

Figure 3.5. Typical DSC curves of (a) Rigid PMTAG Polyol Foam and (b) Flexible PMTAG

Polyol Foam. ........................................................................................................................ 111

Figure 3.6. (a) Compressive strength versus strain curves of PMTAG Polyol foams (a) rigid

foam (b) flexible foams. ....................................................................................................... 113

Figure 3.7. Density (kg/m3) versus compressive strength (MPa) of PMTAG Polyol foams at

6% and 10% deformations (a) rigid foam (b) flexible foam. ............................................... 114

Figure 3.8. (a) Recovery of PMTAG Flexible Foam as a function of time (min); (b) Recovery

of PMTAG Flexible Foam after 48 h as a function of density. ........................................... 116

Figure 4.1. Crystallization thermograms of PMTAG obtained at 0.1 °C/min, 1 °C/min and 5

°C/min. ................................................................................................................................. 130

Figure 4.2. Typical DSC thermograms of the liquid (LF) and solid fractions (SF) of PMTAG.

(a) cooling and (b) heating (both at 5 C/min) ..................................................................... 136

Figure 4.3. DTG of LF- and SF-Polyols ............................................................................. 142

xiv

Figure 4.4. DSC thermograms of LF- and SF-Polyols obtained from the liquid fractions and

solid fractions of PMTAG during (a) Cooling (5.0 C/min), and (b) subsequent heating (5

°C/min). ................................................................................................................................ 144

Figure 4.5. (a) Shear rate- shear stress of LF-Polyol), (b) viscosity versus temperature of LF-

and SF-Polyols. Solid lines in (a) are fits to the Herschel-Bulkley model (Eq. 4.1). .......... 145

Figure 4.6. Typical FTIR spectra of the rigid (RF) and flexible foams (FF) prepared from LF-

Polyol. .................................................................................................................................. 147

Figure 4.7. SEM images of rigid and flexible LF-Polyol foams: (a) rigid foam, (b) flexibe

foam ..................................................................................................................................... 148

Figure 4.8. (a) DTG of rigid (RF) and flexible (FF) LF-Polyol foams ............................... 149

Figure 4.9. DSC thermogram of rigid (RF) and flexible (FF) LF-Polyol foams ................ 150

Figure 4.10. Compressive strength versus strain curves of (a) Rigid LF-Polyol foam of

density 163 kg/m3 (RF) and (b) Flexible LF-Polyol Foam of density 161 kg/m3 (FF). ...... 151

Figure 4.11. Recovery of LF-Polyol Flexible Foam (FF) as a function of time (min) ....... 152

Figure 5.1. DTG profiles of B3- and B4-Green Polyols ..................................................... 176

Figure 5.2. DSC thermograms of B3-, and B4-Green Polyols obtained during (a) Cooling,

and (b) subsequent heating (5 °C/min). ............................................................................... 177

Figure 5.3. Shear rate- shear stress of PMTAG Green Polyols. (a) B3-Green Polyol (b) B4-

Green Polyol, respectively. .................................................................................................. 179

Figure 5.4. Viscosity versus temperature curves obtained during cooling (1 °C/min) of B3-

Green Polyol (empty circles) and B4-Green Polyol (empty triangles). Dashed lines are guides

for the eye. ........................................................................................................................... 179

xv

Figure 5.5: Pictures of rigid and flexible foams from B3-and B4-Green PMTAG Polyols. (a)

B3-Green Polyol rigid foam of density 145 kgm-3 (B3-RF145), (b) B3-Green Polyol flexible

foam of density 162 kgm-3 (B3-FF162), (c) B4-Green Polyol rigid foam of density 166 kgm-

3 (B4-RF166).and (d) B4-Green Polyol flexible foam of density 156 kgm-3 (B4-FF156) .. 180

Figure 5.6. Typical FTIR spectra of rigid (RF) and flexible (FF) B4-Green Polyol foam. 181

Figure 5.7. SEM micrographs of (a) B4-Green Polyol rigid foam and (b) B4-Green Polyol

flexible foam ........................................................................................................................ 183

Figure 5.8. DTG curves of B4-Green Polyol rigid foam (B4-RF) and B4-Green Polyol

Flexible Foam (B4-FF). ....................................................................................................... 185

Figure 5.9. DSC heating thermogram (2nd cycle) of the B4-Green Polyol rigid (B4-RF) and

flexible foams (B4-FF): arrow 1 indicates lowTg , arrow 2 indicates intTg and arrow 3

indicates highTg . ..................................................................................................................... 186

Figure 5.10. Compressive strength versus strain curves of (a) Rigid foams: B3-RF145 (B3-

Green Polyol rigid foam of density 145 kgm-3), B4-RF166 (B4-Green Polyol rigid foam of

density 166 kgm-3) (b) Flexible foams. B3-FF162 (B3-Green Polyol flexible foam of density

162 kgm-3), B4-FF156 (B4-Green Polyol flexible foam of density 156 kgm-3). ................. 187

Figure 5.11: Recovery (%) in thickness of B4-FF156 (B4-Green Polyol flexible foam of

density 156 kgm-3) versus time. ........................................................................................... 190

Figure A 1: 1H-NMR of Epoxidation of PMTAG in Ethyl Acetate. Terminal double bond

left : >60% ............................................................................................................................ 205

Figure A 2: 1H-NMR of Epoxidation of without solvent. No double bond detected. Formic

ester polyol formed. Terminal double bond left : >60% ...................................................... 205

xvi

Figure A 3: 1H-NMR of Epoxidation of with reduced ratio of H2O2 and HCOOH. Terminal

double bond >40% and Internal double bond >5% ............................................................. 206

Figure A 4. HPLC of PMTAG Polyol Fractions (F1-F8) .................................................. 212

Figure A 5: Crystallization thermograms of (a) LF(D)-PMTAG , (b)SF(D)-PMTAG obtained

at 5 °C/min and heating profiles of (c) LF(D)-PMTAG , (d) SF(D)-PMTAG at 5 °C/min..

.............................................................................................................................................. 214

Figure A 6: Crystallization thermograms of (a) LF(S)-PMTAG , (b)SF(S)-PMTAG obtained

at 5 °C/min and heating profiles of (c) LF(S)-PMTAG , (d) SF(S)-PMTAG at 5 °C/min. . 215

Figure A7. 1H-NMR spectra of SF-PMTAG ...................................................................... 217

Figure A 8. 1H-NMR spectra of LF-PMTAG ..................................................................... 218

Figure A 9. 1H-NMR spectra of LF-Polyol ......................................................................... 220

Figure A 10. 1H-NMR spectra of SF-Polyol ....................................................................... 221

Figure A 11: 1HNMR of Selected Polyols ......................................................................... 226

Figure A 12. GPC chromatogram of B3-Green Polyol (B3), B4-Green Polyol (B4) and

standard PMTAG polyol (S). ............................................................................................... 230

List of Schemes

Scheme 1.1: Reaction of isocyanate and alcohol to form urethane linkage ............................ 4

Scheme 1.2: Possible reactions during polyurethane foam preparation .................................. 5

Scheme 1.3: General formula of polyalkylene oxide (polyether) polyol ................................ 7

Scheme 1.4: General formula of polyester polyol ................................................................... 7

Scheme 1.5: General structure of a triacylglycerol (TAG); R1, R2 and R3 are fatty acids, and

may or may not be the same..................................................................................................... 8

xvii

Scheme 1.6: Ozonolysis of vegetable oil TAGs to produce polyols[47]. ............................. 11

Scheme 1.7: Hydroformylation of vegetable oil TAGs to produce polyols. ......................... 12

Scheme 1.8: Transesterification of vegetable oil TAGs using glycerol to produce polyols . 13

Scheme 1.9. Epoxidation reaction of TAG to yield polyol ................................................... 14

Scheme 1.10. Representation of olefin metathesis reaction [100]. Forward reaction (from left

to right) shows the self -metathesis reaction; reverse reaction (from right to left) gives the

cross metathesis reaction. ....................................................................................................... 20

Scheme 2.1. Representation of olefin metathesis reaction. ................................................... 46

Scheme 2.2. Metathesis reaction of triolein with 1-butene. n=0, the fatty acid is 9-denenoic

acid (D), n= 2, the fatty acid is 9-dodecenoic acid (Dd), and n= 8, the fatty acid is oleic acid

(O). ......................................................................................................................................... 55

Scheme 2.3. Possible TAG structures composing PMTAG. n=0, 2, 8; m= 11 to 20. .......... 56

Scheme 2.4. Synthesis of PMTAG Polyol (n=0, 2, 8; m=11 to 20) ...................................... 69

Scheme 2.5. Diol structures produced from oleic acid, 9-dodecenoic acid and 9-decenoic acid

present in the PMTAG as a result of epoxidation followed by hydroxylation. ..................... 76

Scheme 2.6. General structures present in PMTAG Polyol (n= 0, 2, 8; m=11 to 20) ........... 82

Scheme 3.1. Cross linked polyurethane foam from MDI and PMTAG Polyols. Hexol is used

as a model polyol structure. ................................................................................................... 99

Scheme 4.1. Synthesis route of polyols from the liquid and solid fraction of PMTAG (n=0, 2,

8; m=11 to 20). ..................................................................................................................... 133

Scheme 4.2. Possible TAG structures in LF-and SF-PMTAG. n=0, 2, 8; m= 11 to 20. .... 139

Scheme 4.3. Possible structures of LF- and SF-Polyols (n= 0, 2, 8; m=11 to 20) .............. 141

Scheme 5.1. Solvent-free synthesis of polyols from PMTAG. n= 0, 2, 8; m= 11 to 20. ... 170

Scheme 5.2. General structures in PMTAG Green Polyol (n= 0, 2, 8; m= 11 to 20) ......... 174

xviii

Scheme A 1. Possible structure of the formic ester polyol .................................................. 206

Scheme A 2. Structures of PMTAG Polyol determined by MS and 1H-NMR .................. 210

Scheme A3. Fatty acid (FA1, FA2 and FA3) structures from the B4-Polyol. .................... 232

xix

List of Tables

Table 1.1: Some common fatty acids in vegetable oils [8]. The first number in brackets gives

is the number of carbon atoms in the fatty acid chain and the second number indicates the

number of double bonds. .......................................................................................................... 8

Table 1.2: Fatty Acid Composition (%) of some typical vegetable oils (Modified from [10,

58, 59]). .................................................................................................................................. 10

Table 2.1. TAG profile of palm oil and corresponding modified TAG in PMTAG. ............ 56

Table 2.2. GC results of methylated PMTAG. ...................................................................... 57

Table 2.3. Relative amounts of saturated and unsaturated structures in PMTAG as determined

by 1H-NMR. ........................................................................................................................... 59

Table 2.4. HPLC analysis data of PMTAG. .......................................................................... 62

Table 2.5. Optimization data for the synthesis of PMTAG Polyola ...................................... 72

Table 2.6. Characterization of PMTAG Polyol fractions ...................................................... 76

Table 2.7. HPLC retention time (RT, min) and relative area (A%) of column chromatography

fraction of PMTAG polyol (F1-F8) obtained from the analysis of the HPLC of PMTAG

Polyol ..................................................................................................................................... 80

Table 2.8. Thermal data of the PMTAG and PMTAG Polyol obtained on cooling and heating

(5 °C/min). onT , offT , and pT , p= 1-6: onset, offset, and peak temperatures, ,C MH : Enthalpy,

C: crystallization and M: melting. ......................................................................................... 85

Table 3.1. Formulation Recipe for Rigid and Flexible PMTAG Polyol Foam ................... 104

Table 3.2. Composition and properties of PMTAG Polyol and diphenylmethane diisocyanate

(MDI) ................................................................................................................................... 105

xx

Table 3.3. Reactivity profile for the processing of PMTAG Polyol rigid and flexible foams

.............................................................................................................................................. 105

Table 3.4. Compressive strength of vegetable polyol based rigid foams from the literature[7,

43]. ....................................................................................................................................... 115

Table 4.1. Fractionation data of PMTAG. a CT : Crystallization temperature; bCt : isothermal

crystallization time ............................................................................................................... 132

Table 4.2. Formulation Recipes for Rigid and Flexible Foams .......................................... 135

Table 4.3. Fatty acid profile of SF-PMTAG and LF-PMTAG calculated based on the relative

area under the characteristic 1H-NMR peaks assuming TAG structures only. The PMTAG

data are provided for comparison purposes. TDB: Terminal double bonds; IDB: Internal

double bonds; FA: Fatty acid; SFA: Saturated fatty acid .................................................... 139

Table 4.4. Compressive strength of LF-PMTAG Polyol Foams at different strain (%): Rigid

LF-Polyol Foam (RF), Flexible LF-Polyol Foam (FF); Rigid PMTAG Polyol Foam (RF-

PMTAG Polyol); and Flexible PMTAG Polyol Foam (FF-PMTAG Polyol) ..................... 151

Table 5.1. Epoxidation reaction temperature and time data for the synthesis of green polyols.

Epx

iniT : Initial temperature of the epoxidation reaction; max

EpxT : highest temperature reached during

the epoxidation reaction; Epx

RT : reaction temperature for epoxidation; Epx

Rt : reaction time 166

Table 5.2. Formulation Recipes for Rigid and Flexible Foams. Amounts are based on 100

parts by weight of total polyol ............................................................................................. 168

Table 5.3. Amount of remaining terminal double bonds (RTDB)1, number of formic acid

units per TAG polyol and terminal OH groups as estimated by 1H-NMR. Iodine value, Acid

value and OH number of PMTAG Green Polyols. .............................................................. 172

xxi

Table 5.4. Compressive strength of rigid foams: B4-RF166 (B4-Green Polyol rigid foam of

density 166 kgm-3) versus RF-165 (PMTAG Polyol rigid foam of density 165 kgm-3)at 6%

and 10 % deformation. Flexible Foams: B3-FF162 (B3-Green Polyol flexible foam of density

162 kgm-3), B4-FF156 (B4-Green Polyol flexible foam of density 156 kgm-3) and FF-156

(PMTAG Polyol flexible foam of density 156 kgm-3) at 10% and 25% deformation. ........ 189

Table A 1. Table showing the characteristic chemical shift values of PMTAG ................. 204

Table A 2. Thermal data of the PMTAG obtained on cooling and heating (at 0.1, 1.0, 5

°C/min). onT , offT and pT , p= 1-6: Onset, offset, and peak temperatures, ,C MH : Enthalpy, C:

crystallization and M: melting. ............................................................................................ 213

Table A 3. Fractionation of PMTAG by crystallization. OnT : onset of crystallization ...... 213

Table A 4. Thermal data of SF- and LF-PMTAG. onT , offT , 1 3T : onset, offset and peak

temperatures (C), SH , OH , and H (J/g): Enthalpy of the stearin and olein portions, and

total enthalpy, respectively. ................................................................................................. 216

Table A 5. 1H-NMR chemical shifts of SF-PMTAG and LF- PMTAG ............................. 219

Table A 6: Chemical shifts (δ) and their integration values from 1HNMR......................... 222

Table A 7. Temperature of degradation at 1, 5 and 10% weight loss (1%

dT ,5%

dT , 10%

dT ,

respectively), DTG peak temperatures ( DT ), and extrapolated onset ( onT ) and offset (offT )

temperatures of degradation of LF- and SF- Polyols ........................................................... 222

xxii

Table A 8. Thermal data of LF- and SF-Polyols obtained on cooling and heating (both at 5

°C/min). Onset ( onT ), offset (offT ), and peak temperatures ( 1 3T ), Enthalpy of crystallization

( CH ), and Enthalpy of melting ( MH ). aShoulder peak ................................................. 223

Table A 9. Temperature of degradation at 1, 5 and 10% weight loss ( 1%

dT , 5%

dT , 10%

dT ,

respectively), DTG peak temperatures ( DT ), and extrapolated onset ( onT ) and offset ( offT )

temperatures of degradation of LF(D)-Polyol Foams .......................................................... 223

Table A 10: Properties of diphenylmethane diisocyanate (MDI) ....................................... 224

Table A 11. 1H-NMR chemical shifts, δ, of B1-, B2-, B3- and B4-epoxy PMTAG. ......... 224

Table A 12. 1H-NMR chemical shifts, δ, of B1-, B2-, B3- and B4-PMTAG Green Polyols

.............................................................................................................................................. 225

Table A 13. Area% of peaks P1 and P2 from GPC ............................................................. 230

Table A 14. Column chromatography, HPLC and 1H NMR data of the fractions of B4-Polyol.

EA: Hx: ratio of ethyl acetate and hexanes, the solvents used for column chromatography.

RT: HPLC Retention time (min); FA1: Fatty acids with terminal double bond (9-decenoic

acid), FA2: Fatty acid with internal double bond (9-dodecenoic acid); FA3: Fatty acid with

internal double bond (oleic acid). The structure FA1, FA2 and FA3 are presented in Scheme

A3. ........................................................................................................................................ 231

Table A15. Thermal data of Green PMTAG Polyols obtained on cooling and heating (both

at 5 °C/min). Onset ( onT ), offset ( offT ), and peak temperatures ( 1 3T ), enthalpy of

crystallization ( CH ), and enthalpy of melting ( MH ). aShoulder peak ......................... 232

xxiii

List of Abbreviations

Acronym Name

B1-Green Polyol Polyol from PMTAG from Batch 1-solvent free method




B3-FF162 B3-Green Polyol Flexible Foam: Density 162 kgm-3

B4-FF156 B4-Green Polyol Flexible Foam: Density 156 kgm-3

B3-RF145 B3-Green Polyol Rigid Foam: Density 145 kgm-3

B4-RF166 B4-Green Polyol Flexible Foam: Density 166 kgm-3

CFC Chlorofluorocarbon

DBTDL Dibutyltindilaurate

DDD 1,2,3-triyl tris(dec-9-enoate)

DDS 3-(dec-9-enoyloxy) propane-1, 2-diyl distearate

DMBNA N,N-dimethylbenzylamine

DMEA N,N-Dimethylethanolamine

DSS 3-(stearoyloxy) propane-1, 2-diyl bis(dec-9-enoate)

DDO 3-(dec-9-enoyloxy) propane-1, 2-diyl oleate

DDP 3-(dec-9-enoyloxy) propane-1, 2-diyl palmitate

DDS 3-(dec-9-enoyloxy) propane-1, 2-diyl distearate

DSS 3-(stearoyloxy) propane-1, 2-diyl bis(dec-9-enoate)

DDdDd 3-(dodec-9-enoyloxy) propane-1, 2-diyl dec-9-enoate

DOO 3-(oleoyloxy) propane-1, 2-diyl bis(dec-9-enoate)

DLO 1-dec-9-oyl-2-linoleoyl-3-oleoyl-sn-glycerol

DOP 1-decenoyl-2-oleoyl-3-palmitoyl-sn-glycerol

DdDdDd 1,2,3-triyl tris(dodec-9-enoate

DdDdS 3-(dodec-9-enoyloxy) propane-1, 2-diyl distearate

DdDL 1-dodecenoyl-2-decenoyl-3-linoleoyl-sn-glycerol

DdDdL 3-(dodec-9-enoyloxy) propane-1, 2-diyl linoleate

DdDdO 3-(dodec-9-enoyloxy) propane-1, 2-diyl oleate

DdDdP 3-(dodec-9-enoyloxy) propane-1, 2-diyl palmitate

DdDP 1-dodecenoyl-2-decenoyl-9-palmitoyl-sn-glycerol

DdLO 1-dodecnoyl-2-linoleoyl-3-oleoyl-sn-glycerol

DdOP 1-dodecenoyl-2-oleoyl-3-palmitoyl-sn-glycerol

Epoxy B1-PMTAG Epoxy of PMTAG from Batch 1-solvent free method

Epoxy B2-PMTAG Epoxy of PMTAG from Batch 2 -solvent free method



FF Flexible Foam

HDI Hexamethylene diisocyanate

HFC Hydrofluorocarbon

HCFC Hydrochlorofluorocarbon

IPDI Isophorone diisocyanate

LF Liquid Fraction

xxiv

IV Iodine Value

LF-Polyol Liquid Fraction from PMTAG Polyol

LF-PMTAG Liquid Fraction of PMTAG

MAG Monoacylglycerols

MDI Diphenylmethane diisocyanate

MTAG Metathesized Triacylglycerol

MLP 1-myristoyl-2-linoleoyl-3-palmitoyl-sn-glycerol

MMM trimyristoylglycerol

MMP 1,2-dimyristoyl-3-palmitoyl-sn-glycerol

OOO Triolein

OOL 1,2-dioleoyl-3-linoleyol-sn- glycerol

OOP 1,2-dioleoyl-3-palmitoyl-sn- glycerol

OLO 1,3-dioleoyl-2-linoleoyl-sn-glycerol

PMTAG MTAG of Palm Oil

PU Polyurethane

PMTAG Polyol Polyol synthesized from PMTAG by solvent method

PMTAG-FF Flexible Foam prepared from PMTAG Polyol

PMTAG-RF Rigid Foam prepared from PMTAG Polyol

PLL 1,2-dilinoleyol-3-palmitoyl-sn- glycerol

PLP 1,3-palmitoyl-2-linoleoyl-sn-glycerol

POL 1-palmitoyl-2-oleoyl-3-linoleoyl-sn-glycerol

POO 1,2-dioleoyl-3-palmitoyl-sn- glycerol

POP 1,3-dipalmitoyl-2-oleoyl-sn-glycerol

POS 1-palmitoy-l,2-oleoyl,3-stearoyl-sn-glycerol

PPM 1,2-dipalmitoyl-3- myristoyl -sn-glycerol

PPO 1,2-dipalmitoyl-3- oleoyl -sn-glycerol

PPP tripalmitoylglycerol

PPS 1,2-dipalmitoyl-3-steroyl-sn-glycerol

TAG Triacylglycerol

RF Rigid Foam

SF Solid Fraction

SF-PMTAG Solid Fraction of PMTAG

SF-Polyol Solid Fraction from PMTAG Polyol

SFA Saturated Fatty Acid

SOO 1,2-dioleoyl-3-stearoyl-sn- glycerol

SOS 1,3-distearoyl-2-oleoyl-sn-glycerol

TAG Triacylglycerol

TDI Toluene diisocyanate

UFA Unsaturated Fatty Acid

xxv

To

My Parents & My Teacher, Dr. Laly A. Pothen

1

1 Introduction

1.1 Motivation and Objectives

Polyurethane (PU) foams are one of the most versatile polymeric materials with

regards to both processing methods and mechanical properties [1, 2]. They are widely used

because of their physical properties such as light weight, good insulation properties,

excellent strength to weight ratio, and impressive sound absorbing properties [1, 2]. The

PU foam market is very large and growing due to high demand across a wide range of

industries such as automotive, building and construction, and packaging [3, 4]; the worth

of the global polymer foams market was $82.6 billion in 2012 and is estimated to reach

$131.1 billion by 2018 [5]. The specific polyurethane foams market value which was 46.8

billion in 2014 is expected to reach $72.2 billion by 2020 [6].

Traditionally, PU foams are prepared by the reaction of diisocyanates or

polyisocyanates with petroleum-derived polyols [1, 7]. Growing concerns surrounding

sustainability, biodegradability, control of carbon dioxide emission and other

environmental problems are driving a strong demand for alternatives to petroleum as a

feedstock for fuels and materials [8]. Vegetable oils are advantageous in this regard because

of their availability in large quantities, renewability and relatively low cost [9-11]. Studies

on the preparation of rigid and flexible PU foams from vegetable oils (VO) were already

reported; for example PU foams from soybean oil [12-15], castor oil [16], safflower oil,

corn oil, sunflower seed oil, linseed oil [17, 18], rapeseed oil [19-21] and cotton seed oil

[22]. However, the dangling chains which remain in the PU foams from the saturated fatty

acids as well as from the omega chains of the unsaturated fatty acid of VOs negatively

2

affect the rigidity of the foams [23]. The regions where dangling chains are present do not

support stress when the sample is loaded. Furthermore, they act as plasticizers, resulting in

reduction of polymer rigidity [24, 25]. This can be addressed by modifying vegetable oils

using more appropriate methods such as olefin cross-metathesis, ozonolysis, fractionation

etc., such that dangling chains are removed.

Palm oil is one of the cheapest, most produced TAG oils, making it an ideal feedstock

replacement at an industrial scale. It is primarily used in foods [26, 27] and is increasingly

sought for the production of industrial materials. Palm oil is typically composed of 95%

triacylglycerols (TAGs), 5% diacylglycerols (DAGs), and other minor components such as

monoacylglycerols (MAGs) with a fatty acid profile ranging typically from C12 to C20

[28, 29]. It has a balanced saturation (~50/50 % of saturates / unsaturates) [30, 31]. Palmitic

acid (P, C16:0) and oleic acid (O, C18:1) with ~43% and ~41%, respectively, are the main

components of palm oil. Palm oil includes ~10% linoleic acid (Li, C18:2), and trace

amounts of linolenic acid (Ln, C18:3) and palmitoleic acid (C16:1). Other representative

saturated fatty acids, which are present in non-significant amounts (< 5 %), in palm oil are

lauric acid (L, C12:0), myristic acid (M, C14:0), stearic acid (S, C18:0) and arachidic acid

(A, C20:0). The TAG profile of palm oil shows a carbon distribution of C46 to C52

consisting of tri-unsaturated (4.8-9.8%), di-unsaturated (31.8-44.4%), mono unsaturated

(38.5-50.3%) and saturated TAGs.

Despite the high saturation, palm oil has been successfully transformed into a variety

of industrial materials [32]. It is increasingly used to make value added products such as

soaps and detergents [33], lubricants [34, 35], biodiesel [30, 36] and surfactant [37]. Palm

oil and its derivatives are also actively investigated as a feedstock for the synthesis of

3

polyols to prepare polyurethanes [32, 38, 39]. However, its larger use in the production of

polyurethanes is affected by its relatively higher levels of saturation (50% fatty acids)

which limits the hydroxyl values of its polyols as compared to the polyols of highly

unsaturated vegetable oil [40]. This restricts the applicability of palm oil-based polyols in

polymer formulations, particularly in rigid polyurethane foams [40].

Cross metathesis [41] is a widely used chemical technique to convert the internal

double bonds of unsaturated fatty acids into terminal double bonds, thereby removing the

dangling chains associated with the unsaturated fatty acids. 1-butene metathesized palm

oil, called PMTAG, is a by-product of the industrial biorefinery that produces 1-decene

and 3,4-dodecene linear aliphatic olefins for the fine chemicals sector. Our industrial

collaborator, Elevence Renewable Sciences (ERS, Bolingbrook, Ill., USA), owns the

intellectual property right to convert palm oil into PMTAG [42]. ERS currently operates a

biorefinery plant in Indonesia which processes 400 million lbs of palm oil, and plans to

build other biorefinery processing plants in North America that will use cross-metathesis

on native plant oils such as soybean oil and canola oil. This will increase the amount of

these types of byproducts; i.e., metathesized vegetable oils. Conversion of these byproducts

into value added products is, therefore, desirable in order to increase the profitability of the

industry.

The present study investigated whether PMTAG can be used to produce rigid and

flexible PU foams. The objective of the study was not only to convert a byproduct into

useful material, but also to contribute to the fundamental understanding necessary to

address the dangling chain issues of vegetable oil derived PU foams. The potential for cross

metathesis of palm oil followed by fractionation of saturated components to address the

4

dangling chain issues of palm oil was investigated. For this purpose, PMTAG was used to

synthesize several polyols with variable hydroxyl value and terminal hydroxyls for the

preparation of rigid and flexible polyurethane foams. The possibility to remove the

saturated components of PMTAG using crystallization fractionation was also investigated

and the fractionated PMTAG was used for the preparation of polyols and polyurethane

foams.

1.2 Background

1.2.1 Polyurethanes

Polyurethanes are macromolecules containing urethane linkages (-NH-CO-O-) that

are formed either based on the reaction of isocyanate (-NCO) groups and hydroxyl groups

[1], or via non-isocyanate pathways, such as the reaction of cyclic carbonates with amines

[43], self-polycondensation of hydroxyl-acyl azides or melt transurethane methods [44].

The most common method to form the backbone urethane group is the reaction of a polyol

and an isocyanate with suitable cross-linking agents, chain extenders, blowing agents and

other additives [45].

Scheme 1.1: Reaction of isocyanate and alcohol to form urethane linkage

Scheme 1.1 shows the formation of a urethane linkage from the reaction of a

hydroxyl group and an isocyanate. The appropriate selection of reactants enables the

5

formation of a wide range of polyurethane products such as polyurethane elastomers [46],

sheets [47], adhesives [48], coatings [49] and foams [23].

1.2.2 Polyurethane foams

As discussed above, polyurethane foams are obtained by the reaction between

polyols and diisocyanates or polyisocyanates in the presence of physical or chemical

blowing agents [1, 7]. Polyurethane foam preparation involves two major simultaneous

reactions: the cross linking reaction (see Scheme1.2a) and the blowing reaction (gas

producing) (scheme 1.2b & 1.2c). The cross linking reaction leads to the formation of the

urethane linkage [50, 51]. The subsequent reaction between isocyanate and water produces

unstable carbamic acid which decomposes further into amine and carbon dioxide (see

Scheme 1.2c). The carbon dioxide gas diffuses into the trapped air bubbles in the reaction

mixture, causing the foam to rise. Scheme 1.2d shows the formation of a urea linkage by

the reaction of excess of isocyanate with amine (see Scheme 1.2c). .

Scheme 1.2: Possible reactions during polyurethane foam preparation

The progress of the polyurethane foaming process can be monitored by the cream

time, gel time and rise time. Cream time is defined as the time at which the polymerization

mixture becomes creamy and brightened. Gel time is the time at which the increasing cross-

6

linking results in a gel-like or syrup-like polymer consistency. Rise time is the time period

between the gel time and end of rise of the foams [1].

Furthermore, the physical properties of foams can be tailored to a large extent by

varying the structure and composition of the reacting monomers, amount of catalyst and

other additives (such as glycerin and water), as well as the reaction conditions used in the

foam preparation [52]. PU foams may be classified as rigid or flexible according to the

compressive strength value, cross link density, and OH value of the starting polyol [1].

Polyols having high molecular weight and low functionality yield flexible polyurethane

foams [53] whilst polyols with low molecular weight and high functionality give rigid

polyurethane foams [54].

1.2.3 Polyols

Polyols are a class of organic compounds with more than one hydroxyl functional

groups. They can be used as monomers for making polyurethanes. The properties of the

polyols such as hydroxyl value, molecular weight and functionality have important effects

on the polyurethane properties [1, 7, 55]. The hydroxyl value of the polyol represents the

reactive hydroxyl functionality in the molecule and is defined as the number of milligrams

of potassium hydroxide (KOH) required to neutralize one gram of acetylated chemicals

containing free hydroxyls [56].

1.2.4 Petroleum Polyols

Traditionally, polyurethane foams are prepared from petroleum derived polyols such

as polyether and polyester polyols [1, 56]. Polyether polyols are widely used for the

7

preparation of polyurethane foams and elastomers [1, 7]. Polyether polyols are obtained by

the polymerization of alkylene oxide initiated by different hydroxyl containing molecules

such as ethylene glycol, propylene glycol or other polyols [7]. Scheme 1.3 represents the

general structure of polyether polyols. The grafting of polymers on the polyether polyol

backbone results in polymer polyols that are widely used for flexible foam applications.

Polyester polyols are molecules with ester linkages used for the preparation of segmented

polyurethane thermoplastics with good mechanical properties [7]. Polyesters are

synthesized by the polycondensation reaction of a diacid, such as adipic or phthalic acid,

with a diol, such as ethylene glycol or propylene glycol [7]. Scheme 1.4 presents general

formula of a polyester polyol.

Scheme 1.3: General formula of polyalkylene oxide (polyether) polyol

Scheme 1.4: General formula of polyester polyol

8

1.2.5 Vegetable Oil Based Polyols

Vegetable oil based polyols are synthesized by the modification of vegetable oil TAGs

at their double bonds or ester linkages by the appropriate chemical reactions [2, 10, 57].

Vegetable oils consist of ~ 95 % triacylglycerols (TAG), which are the triesters of fatty

acids and glycerol.

Scheme 1.5: General structure of a triacylglycerol (TAG); R1, R2 and R3 are fatty

acids, and may or may not be the same.

Scheme 1.5 shows the general structure of a TAG. R1, R2 and R3 are aliphatic long

chain fatty acids usually containing 16-18 carbon atoms in their linear back bone. The fatty

acid profiles of TAGs are not unique; they vary from vegetable oil to vegetable oil. The

properties of vegetable oils, therefore, are highly dependent on their fatty acid composition.

The major saturated and unsaturated fatty acids present in vegetable oils are listed on the

Table 1.1, and the typical profiles of some of the more common vegetable oils are

presented in Table 1.2.

9

Table 1.1: Some common fatty acids in vegetable oils [8]. The first number in

brackets gives is the number of carbon atoms in the fatty acid chain and the second number

indicates the number of double bonds.

(C16:0)

(C16:1)

(C18:0)

(C18:1)

(C18:2)

(C18:3)

(C18:1 OH)

10

Table 1.2: Fatty Acid Composition (%) of some typical vegetable oils (Modified

from [10, 58, 59]).

Seed Oil

Fatty Acid Composition (% of total fatty acids)

Palmitic

acid

Palmitoleic

acid

Stearic

acid

Oleic

acid

Linoleic

acid

Linolenic

acid

Sunflower 5.2 0.1 3.7 33.7 56.5 0.0

Soybean 10.1 0.0 4.3 22.3 53.7 8.1

Cottonseed 23.0 0.0 2.3 15.6 55.6 0.3

Corn 11.6 0.0 2.5 38.7 44.7 1.4

Olive 13.8 1.4 2.8 71.6 9.0 1.0

Palm 44.8 0.0 4.6 38.9 9.5 0.4

Rapeseed 4.6 0.3 1.7 60.1 21.4 11.4

Linseed 5.6 0.0 3.2 17.7 15.7 57.8

Sesame 9.6 0.2 6.7 41.1 41.2 0.7

Cashew

nut

11.6 0.3 8.9 61.5 17.1 0.0

Canola 4.0 - - 2.0 64.0 19.0 9.0

Castor* 2.0 - - 1.0 7.0 3.0 - -

* ricinoleic acid content = 87%

Ozonolysis [2, 47, 65], hydroformylation [2, 59], epoxidation [2, 66] and

transesterification [2, 67] are some of the key modification techniques that have been used

for the insertion of hydroxyl groups at unsaturated sites in the TAGs. Furthermore, the

selection of the synthetic method has a large influence on the type of polyol and their

properties [68, 69]. For example, the hydroxyl value (OH value) of a given polyol - which

11

has huge impact on the physical properties of the resulting foam- varies with the different

modification techniques adopted for the synthesis of polyol [70].

Ozonolysis [47] followed by hydrogenation gives polyols with terminal hydroxyl

groups [68]. Scheme 1.6 shows the ozonolysis of TAGs to produce polyols. This method

uses ozone to cleave and oxidize the double bonds in TAGs into the corresponding ozonide

intermediates. The ozonides thus produced are further hydrogenated into polyols using

Raney Nickel catalyst [68]. However the polyols prepared by this method contain only one

hydroxyl group per double bond and may show high acid values due to oxidation during

and/or after ozonolysis.

Scheme 1.6: Ozonolysis of vegetable oil TAGs to produce polyols[47].

Hydroformylation [70-72], also called oxo synthesis, is another route for producing

polyols from vegetable oils. The double bonds in TAGs undergo hydroformylation in the

presence of syn gas (a carbon monoxide and hydrogen gas mixture), and suitable catalysts

such as rhodium or cobalt, to give the corresponding formylated intermediate. This

intermediate is further hydrogenated to give polyol having primary hydroxyl groups [59,

12

73]. This method, however, utilizes expensive complex catalysts [70], retains the dangling

chains of the omega fatty acids, and like ozonolysis, gives polyols which possess only one

OH group per carbon-carbon double bond. Scheme 1.7 shows the hydroformylation

reaction of vegetable oil TAGs followed by reduction to produce polyols.

Transesterification [67, 74] with glycerol is another method for the synthesis of

polyols from vegetable oil based TAGs. Scheme 1.8 shows the synthesis of polyols by

transesterification process.

Scheme 1.7: Hydroformylation of vegetable oil TAGs to produce polyols.

13

Scheme 1.8: Transesterification of vegetable oil TAGs using glycerol to produce polyols

Epoxidation [75, 76] of vegetable oils followed by ring opening is a well-established

route for the preparation of vegetable oil based polyols. Scheme 1.9 shows the epoxidation

of vegetable oil TAGs into the corresponding epoxide and its subsequent ring opening to

yield TAG derived polyols. In this method the double bonds are converted into oxirane

moieties by treating with peracetic or performic acid formed in situ by the reaction of

hydrogen peroxide (H2O2) and acetic acid or formic acid, respectively [75]. Epoxidation

followed by acid-catalyzed ring opening using reagents such as HClO4/water allows the

conversion of double bonds into two hydroxyl groups per double bond. This is not possible

by the synthesis of polyols by ozonolysis or hydroformylation methods. Also, the epoxide

groups can be opened using different nucleophilic reagents such as alcohols (R-OH),

hydrogen halides (R-X) and thiols (R-SH) to produce differently functionalized polyols

having variable OH values [77, 78].

14

Scheme 1.9. Epoxidation reaction of TAG to yield polyol

1.3 Factors Determining the Properties of PU Foams

1.3.1 Effect of Polyol Structure

The structure and functionality of polyols are very important factors which determine

the physical properties of polyurethane foam properties such as compressive strength,

thermal stability and glass transition temperature [70]. For example, the molecular weight,

hydroxyl value, position of hydroxyl groups and presence of dangling chains of polyols

have significant effects on the final properties of the polyurethanes derived from them [56,

59].

It was reported that the glass transition temperatures of the polyurethanes increased

to higher temperatures with increasing OH values and, therefore, cross-link density of the

polyol [79, 80]. This suggests that the rigidity of the polyurethane foams can be enhanced

by increasing the OH value of the polyols. Also, terminal or primary hydroxyl groups

15

present in the polyol structure display higher reactivity during polymerization reactions

and produce higher crosslinking polymer networks compared to polyols having only non-

terminal hydroxyl groups [81]. Polyols having terminal hydroxyls and, therefore, no

dangling chains, synthesized from cross metathesized triolein and canola oil, imparted

excellent mechanical properties such as higher tensile strength and modulus in

polyurethanes compared to soybean oil polyol which possessed dangling chains and only

internal hydroxyls [65, 82, 83]. The polyurethane prepared from terminal hydroxyl polyols

with no dangling chains behave as rigid plastics having glass transition temperature at 55

ºC [83]. In case of the preparation of rigid polyurethane foams, the addition of primary

hydroxyl cross linkers such as glycerine, starch etc. increases the rigidity of the material

with more uniform sized cells [52, 69]. Thus, the selection of the synthetic strategies is

highly important in order to achieve the necessary architecture in the polyol structure,

which imparts essential rigidity to the resulting polyurethanes produced.

1.3.2 Effect of Isocyanate

Like polyols, diisocyanates also contribute significantly to the crosslinking density

of PUs. Commercially available aromatic diisocyanates such as MDI (Diphenylmethane

diisocyanate) and TDI (Toluenediisocyanate), and aliphatic diisocyanates such as IPDI

(Isophorone diisocyanate) and HDI (Hexamethylene diisocyanate), are widely used in the

preparation of polyurethane foams [13]. Bio-based lipid diisocyanates synthesized from

lipids (oleic acid) have also been used for the preparation of polyurethane thermoplastics

with fairly good properties [84, 85].

16

MDI and TDI are the most common diisocyanates that are employed for the

preparation of rigid polyurethane foams. It has been shown that polyurethane foams

prepared with MDI possess compact and uniformly distributed cells with higher rigidity

compared to those prepared with TDI [81]. The high rigidity of MDI based polyurethanes

is due to its two aromatic rings and the high molecular weight compared with TDI [52, 81].

Also, the reaction rate with MDI is slower than with TDI [13, 86]. Thus, it allows sufficient

time for the formation of a stable three dimensional network that can withstand the pressure

of the blowing reaction without the breakage of the foam cells.

1.3.3 Effect of Catalyst

The catalysts used for the polyurethane foaming process play an important role in

balancing the blowing and gelling reaction in order to produce desired foams [1]. Without

the proper catalyst, competition of the gelling and the blowing reactions occur during

foaming, leading to the collapse of the cells in the foams [81].

Polyurethane foaming catalysts are generally amine compounds or organometallic

complexes [1, 7]. The catalyst concentration controls the rate of the two competing

reactions and by changing the ratio of the catalyst the resulting properties of the polymer

foams can be varied. The catalyst amounts should be balanced for the desired gel time,

cream time and tack-free time, and significantly affects the cell morphology and the density

of the foams [87]. N,N-dimethylbenzylamine (DMBNA) is one of the catalysts widely used

for the preparation of polyurethane foams. Tin II caprylate, which is an organo tin catalyst,

has been used for rigid polyurethane preparation [52]; increasing the amount of tin II

17

caprylate during polymerization enhanced the number of closed cells with decreased

gelation time.

Dibutyltindilaurate (DBTDL) and N, N-Dimethylethanolamine (DMEA) are the two

most common catalysts which are very cheap and widely used in polyurethane foam

preparation. DBTDL is a cross linking catalyst which favours the gelling reaction, and

DMEA is a co-catalyst which functions as a blowing catalyst during the polymerization

process [1, 7]. The appropriate ratios of DBTDL and DMEA is necessary, therefore, to

control the foaming process. In most cases both the catalyst and co-catalyst are fixed to the

same ratio. Narine et.al, for example, determined that a fixed ratio (1 part by weight) of

both DBTDL and DMEA was optimal for the preparation of rigid polyurethane foams of

fairly good compressive strength from terminal hydroxyl polyols [68].

1.3.4 Effect of Blowing Agent

Polyurethane foam production may be aided by the inclusion of a blowing agent in

the polymer formulation. The blowing agent promotes the release of a blowing gas which

is responsible for the formation of cell voids in the foam. The blowing agent may be a

physical blowing agent or a chemical blowing agent.

The physical blowing agent is a gas or liquid that does not chemically react with the

polyisocyanate composition [7]. A liquid physical blowing agent typically evaporates into

a gas when heated, and returns to a liquid when cooled. Such blowing agents are generally

inert or they have low reactivity and, therefore, it is likely that they will not decompose or

react during the polymerization reaction. The physical blowing agent typically reduces the

thermal conductivity of the polyurethane foam [1]. Examples of physical blowing agents

18

include carbon dioxide, nitrogen gas, acetone, and low-boiling hydrocarbons such as

cyclopentane, isopentane, n-pentane, and their mixtures. Note that the most typical physical

blowing agents have a zero ozone depletion potential; blowing agents such as

chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), and hydrochlorofluorocarbons

(HCFCs) have been used in the past, but these were completely abandoned due to

environmental issues [1].

Chemical blowing agents refer to blowing agents which chemically react with the

polyisocyanates. Water is the commonly used chemical blowing agent for reaction with

polyisocyanates. Increased amount of water content in the polymerization mixture causes

expansion of the foam cells and the associated reduction in the thickness of the cell wall

[81]. It was observed that with a water content beyond six (6) parts percent by weight, for

example, the foaming reaction becomes too rapid and the corresponding foams exhibit poor

compressive properties [52], whilst a water content of two (2) parts percent by weight gives

optimal compressive strength properties for rigid foams [86].

1.3.5 Effect of Surfactant

Surfactants are added into the polymer formulation in order to reduce the interfacial

tension between the monomers and the aqueous phase [88]. The surfactant controls the size

of the foam cells and prevents the collapse of the cells [81]. Silicone based surfactants have

been found very effective in producing uniform sized foam cells by creating good air

permeability. Polyether-modified polysiloxane (TEGOSTAB B-8404) is one of the widely

used silicone surfactant in PU rigid foam formulations [68].

19

1.4 Problems of Vegetable oil Derived PU Foams

The unsaturated fatty acids present in vegetable oils possess internal double bonds.

Except when ozonolization is used, functionalization of internal double bonds to give

polyols retain the omega dangling chains which, upon polymerization, result in incomplete

crosslinking and imperfections in the polymer network [23, 89]. This, added to the non-

reactive saturated fatty acid already present in the vegetable oil, result in an elevated

dangling chain effect which further reduces the polymer rigidity. The regions where

dangling chains are present do not support stress when the sample is loaded, and act as

plasticizers to reduce polymer rigidity [24, 25]. In fact, the presence of dangling chains and

the position of the hydroxyl groups in the fatty acid chain along with the hydroxyl value

and molecular weight of the polyol have been cited as the most important structural features

which affect the properties of polyurethanes derived from vegetable oils [24, 25, 70, 90].

These issues are generally mitigated through the chemical transformation of the natural oil

into a more functional feedstock and judicious choice of methods for synthesizing the

polyols [89].

1.5 Rectification of Dangling Chain Issue

1.5.1 Olefin Metathesis

Olefin metathesis has been used commercially in the Philips Process for decades now

for the conversion of propylene into ethylene and butene [91]. It has been used in the Shell

Higher Olefin Process for the production of neohexene for the application of synthetic

masks [92, 93]. It has been used since 1972 on TAG oils and unsaturated fatty acid

derivatives to produce fine chemicals, substrates and materials, many of which serve as or

20

are potential petrochemical replacements [94, 95]. In fact, olefin metathesis holds

exceptional promise in oleochemistry for many industries which produce value added

monomers from vegetable oils [96-100]; it can be used to increase the molecular diversity

and reactivity of natural oils, and, therefore, their potential for transformation into

functional materials [101, 102].

Scheme 1.10. Representation of olefin metathesis reaction [100]. Forward reaction

(from left to right) shows the self -metathesis reaction; reverse reaction (from right to left)

gives the cross metathesis reaction.

Olefin metathesis (Scheme 1.10) is a reversible reaction involving the exchange of

the alkylidene groups between the reactant alkene moieties in the presence of catalysts,

typically transition metal complexes [100, 103]. Olefin metathesis is categorized further as

self-metathesis and cross metathesis [96, 100]. In the self-metathesis reaction (forward

reaction in Scheme 1.10), the same olefin molecules react to produce two different olefin

products. The self-metathesis of TAGs results in a complex mixture comprising linear

oligomers (from dimer to pentamer), macrocyclic structures, cross-linked polymers, as well

as trans-/cis isomers [104]. In a cross metathesis reaction (reverse reaction in Scheme

1.10), two different olefins are reacted to produce a new olefin product. Cross-metathesis

of a vegetable oil with an olefin results in a metathesized TAG (MTAG) mixture including

modified TAG structures not present in the natural oil; for example, carbon-carbon terminal

double bond moieties [105, 106]. The actual composition of a metathesis product is highly

21

dependent on the reaction conditions, such as starting materials, temperature and type of

catalyst. Thus, the product composition of a given metathesis reaction can be controlled by

a judicious selection of the reaction conditions [107-109].

Cross-metathesis of TAG oils can be used to produce feedstock with increased

molecular diversity and reactivity suitable for the production of more functional polyols

and, therefore, polyurethanes, as has been demonstrated with triolein [89]. Cross-

metathesis, among other modifications, results in low molecular weight metathesized

products with terminal double bonds and shortened unsaturated fatty acid moieties [103,

110]. The resulting polyols, therefore, possess terminal hydroxyl groups, facilitating the

formation of polyurethane networks with significantly reduced dangling chains compared

to natural oil polyols [89].

Ethylene cross-metathesis is one of the cheapest and industrially viable techniques

for selective transformation of vegetable oils, but it still has problems related to low yield,

poor selectivity and low catalyst turnover due to complicated reaction pathways [99, 100].

For example, the cross-metathesis reaction of crude palm oil with ethylene produces

terminal alkene moieties such as 1-decene and 1-heptene, but in low yields [111]. Cross-

metathesis with 2-butene, on the other hand, gives high conversions and catalyst turnovers

[112, 113]. However, cross-metathesis with the internally unsaturated 2-butene does not

give TAG products with terminal carbon-carbon double bonds.

Alternately, cross-metathesis with 1-butene will result in a mixture of terminal

double bonds and fatty acid moieties with shortened dangling chains (C3) in high yields.

In fact, Elevence Renewable Science (ERS) presently uses a protected 1-butene metathesis

22

reaction of vegetable oil TAGs to produce 1-decene and 3,4-dodecene [42], whereby the

metathesized vegetable oil is a by-product of the biorefinery. This by-product is, therefore,

a suitable starting material for the production of bio-based polyols with terminal hydroxyl

groups and reduced dangling chain content for use in polyurethane foam production. No

such work has been reported so far regarding the study of structure and composition of 1-

butene cross metathesized palm oil (PMTAG) and its application for polyols and

polyurethane foams.

1.5.2 Fractionation by Crystallization

Since the 1-butene cross-metathesis reaction only modifies the unsaturated fatty

acids present in palm oil, the composition of the saturated fatty acids remain unaffected.

The non-reactive saturated fatty acids present in the 1-butene metathesized palm oil,

however, sterically hinder and lessen the reactivity of the unsaturated fatty acids present in

it. The dangling chain action and the steric hindrance of the saturated stearin fraction can

be a problem, therefore, in the commercialization of 1-butene metathesized palm oil for the

preparation of polyol for the polyurethane industry.

In multicomponent systems, the difference in the solubility and solidification of the

different components can be exploited for their separation by fractional crystallization [27].

This approach is widely used by the oleochemical industries for the fractionation of edible

oils for food and other advanced applications [114]. It is employed to separate the high-

and low- melting components of edible oils based on their crystallization temperatures

[115], which depend on their molecular weight and the degree of the unsaturation. The

separated fractions display unique chemical and physical properties.

23

Fractionation by crystallization can be further subdivided into dry (neat

fractionation) and solvent assisted fractionation (fractionation procedure using solvent)

[116]. Solvent assisted fractionation is highly dependent on the solubility of the

components in the selected solvent. Solvent assisted crystallization of oils is a fast process

and gives good yield while the dry fractionation may require multiple steps for the

completion.

A large body of literature already exists on the successful fractionation of palm oil

to into its high melting (stearin) and low melting (olein) fractions for various food and

industrial feedstock applications[117-119]. Fractionation by crystallization is, therefore, an

established means of reducing the saturated content in the 1-butene metathesized palm oil

so as to produce a highly reactive feedstock for polyurethane production.

1.6 Hypotheses

The purpose of this study was to convert PMTAG into a useful material for the

preparation of the rigid and flexible PU foams and to contribute to the fundamental

understanding necessary to address the dangling chain issues of TAGs comprised of omega

unsaturated fatty acids. It is expected that the reduction of the dangling chain limitations

of palm oil by 1-butene cross metathesis, and the removal of the highly saturated stearin

fraction by fractional crystallization will, together, allow for the use of palm oil in rigid

polymer applications. The same approach can also be applied to other vegetable oils rich

in omega unsaturated fatty acids and saturated fatty acids such as canola and soybean oils,

allowing for the preparation of viable bio-based alternatives to petroleum based

polyurethanes. The following hypotheses were investigated in this work:

24

Hypothesis 1: The terminal hydroxyl PMTAG polyols will produce more rigid

polyurethane foams compared to those obtained from palm oil, soybean oil and canola oil.

In order to address Hypothesis 1, the following objectives were identified:

Establish the structure, chemical composition and physical properties of 1-butene cross

metathesized palm oil (PMTAG)

Synthesize terminal hydroxyl polyols of maximum OH value from PMTAG by

epoxidation followed by hydroxylation procedure.

Establish the structure, chemical composition and physical properties of PMTAG

polyol.

Prepare rigid foams from PMTAG polyols and test their physical properties and

compare with palm oil, soybean oil and canola oil derived foams from literature.

Hypothesis 2: Flexible foams can be prepared from PMTAG polyol by suitable alteration

in the formulation recipe of the rigid foams.


Prepare PU foams from the PMTAG polyol using low catalyst ratio and no glycerine

cross linker and test their recovery and compressive strength to check its suitability for

flexible foam applications.

Hypothesis 3: Fractionation of PMTAG by dry and solvent assisted crystallization will

remove the highly saturated stearin fraction (solid fraction) of PMTAG, leaving behind a

highly reactive olein fraction (liquid fraction). Polyols derived from the olein fraction of

25

PMTAG will possess higher OH values compared to the PMTAG polyol and will make

highly rigid foams compared to rigid PMTAG polyol foams.


Fractionate PMTAG using dry and solvent mediated crystallization to separate olein

rich and stearin rich fractions.

Synthesize polyols from different fractions of PMTAG.

Prepare rigid foams from liquid/olein fraction of PMTAG and test their compressive

properties, and compare with PMTAG polyol rigid foams.

Hypothesis 4: Flexible foams can be prepared from olein fraction (liquid fraction) of

PMTAG by varying the formulation recipe.


Prepare PU foams from the liquid fraction PMTAG polyol using low catalyst ratio and

no glycerine cross linker and test their recovery and compressive strength to check its

suitability for flexible foam applications.

Hypothesis 5: Green PMTAG polyols can be prepared by solvent free epoxidation

followed by hydroxylation of PMTAG, and their OH values can be controlled by tuning

the degree of epoxidation based on the reaction conditions. The rigidity of the Green

PMTAG polyol foams will increase with increasing OH value and terminal hydroxyls in

the polyol.


26

Synthesize polyols from PMTAG using solvent free pathway of epoxidation and

hydroxylation reaction.

Control the reaction parameters of epoxidation process to produce polyols with

controlled hydroxyl values

Prepare flexible foams from Green PMTAG polyols using low catalyst ratio and no

glycerine cross linker and test their recovery and compressive strength with flexible

PMTAG polyol foams.

Prepare rigid foams from Green PMTAG Polyol and compare the rigidity with rigid

PMTAG polyol foam.

1.7 Thesis Outline

The rest of this thesis is organized into six (6) chapters. Chapter 2 will describe the

structure, chemical composition and physical properties of PMTAG and PMTAG polyol.

Chapter 3 will describe the preparation and physical characterization of rigid and flexible

polyurethane foams prepared from PMTAG polyol (i.e., Hypotheses 1 and 2). Chapter 4

will address the use of dry and solvent mediated fractionation of PMTAG for the effective

removal of the highly saturated stearin fraction and the preparation of polyols and

polyurethane foams from the fractionated PMTAG (i.e., Hypotheses 3 and 4). Chapter 5

will report on the preparation of green polyols with controlled OH values and their

corresponding rigid and flexible foams (i.e., Hypothesis 5). Finally, Chapter 6 will give

the conclusion and implications of this work.

27

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43

2 1-Butene Metathesized Palm Oil & Polyol Derivatives:

Structure, Chemical Composition and Physical Properties

2.1 Introduction

Growing concerns surrounding sustainability, biodegradability, control of CO2

emission and other environmental problems are driving a strong demand for alternatives to

petroleum as a feedstock for fuels and materials. Vegetable oils are advantageous in this

regard because of their availability in large quantities, renewability and relative low cost

[1]. Furthermore, their triacylglycerol (TAG) structure is attractive for the chemical

industry as it offers ready sites, such as the double bond and the ester, for chemical

transformation [2]. There currently exists an important oleochemical industry that uses a

large array of standard as well as novel chemical reactions on TAG oils to make a variety

of fine chemicals and materials such as fuels, polymers, lubricants, waxes and cosmetics

[3-5].

The development of polyurethanes from renewable and environment-friendly

feedstock is of particular importance as the market is very large and growing due to high

demand across industries such as automotive, building and construction, and packaging.

The worth of the global polymer foams market was $82.6 billion in 2012 and is estimated

to reach $131.1 billion by 2018 [6]. A relatively large body of literature reporting on the

synthesis of polyols and polyurethanes from natural oils is available (see for example PU

foams from soybean oil [7, 8], safflower oil, corn oil, sunflower seed oil, linseed oil [9],

rapeseed oil [10], palm oil [11], cotton seed oil [12]).

44

However, the development of polyol substrates and PU foams from natural oils is

challenging. The introduction of hydroxyl groups at the positions of double bonds can be

achieved by various methods [3]. Some of the methods are ozonolysis followed by

hydrogenation [13, 14], hydroformylation followed by hydrogenation [4, 15], epoxidation

followed by ring opening [16, 17] or bioconversion directly to polyols [18]. These synthesis

methods produce polyols of distinctive hydroxyl value, distribution and position of the

hydroxyl groups which result in polyurethane networks with vastly different properties [14,

15, 19]. In many instances however, the functionalization of the double bonds leaves

significant amounts of dangling chains because of their internal location on the fatty acids.

The presence of relatively large amounts of non-reactive moieties further reduce the

suitability of the polyols, especially to make rigid polyurethane foams because the regions

where dangling chains are present do not support stress when the sample is loaded, and act

as plasticizers that reduce polymer rigidity. These issues are generally mitigated through

the chemical transformation of the natural oil and judicious choice of methods of

synthesizing the polyols [20].

Palm oil is a particularly important TAG oil. It is the most produced and one of the

cheapest renewable commodity oils in the world, making it an ideal feedstock replacement

at an industrial scale. It is primarily used in foods [5, 21] and increasingly sought for the

production of industrial materials. Palm oil is typically composed of 95% TAGs and 5%

diacylglycerols (DAGs) and other minor components such as monoacylglycerols (MAGs)

with a fatty acid profile ranging typically from C12 to C20 [22, 23]. It has a balanced

saturation (~50/50 % of saturates / unsaturates) [24, 25]. Palmitic acid (P, C16:0) and oleic

acid (O, C18:1) with ~43% and ~41%, respectively, are the main components of palm oil.

45

Palm oil includes ~10% linoleic acid (Li, C18:2), and trace amounts of linolenic acid (Ln,

C18:3) and palmitoleic acid (C16:1). Other representative saturated fatty acids in palm oil

are lauric acid (L, C12:0), myristic acid (M, C14:0), stearic acid (S, C18:0) and arachidic

acid (A, C20:0). The TAG profile of palm oil shows a carbon distribution of C46 to C52

consisting of tri-unsaturated (4.8-9.8%), di-unsaturated (31.8-44.4%), mono unsaturated

(38.5-50.3%) and saturated TAGs [5].

Despite high saturation, palm oil has been successfully transformed into a variety of

industrial materials [26]. It is increasingly used to make value added products such as soaps

and detergents [27], lubricants [28, 29], biodiesel [24, 30] and surfactant [31], etc. Palm oil

and its derivatives are also actively investigated as a feedstock for the synthesis of polyols

to prepare polyurethanes [11, 26, 32]. However, its larger use for the production of

polyurethanes is hindered because of its relatively higher saturation level (50% fatty acids)

which cap the hydroxyl value of its polyols, which adds to the structural limitations

inherent to TAG oils [22]. Typical palm oil-based polyols produced so far usually have

hydroxyl values of less than 200 mg KOH g−1 [33] limiting their applicability in some

polymer formulations, particularly in rigid polyurethane foams. Although some successful

examples through chemical transformation of the natural oil are reported in the literature,

such as for example, the transformation of the TAGs of the natural palm oil into

monoacylglycerols (MAG) before functionalization and polymerization [26, 34], no

significant breakthroughs have been made with palm oil in this area.

More research around the transformation of the natural oil such as targeted chemistry

and proper processing techniques, is needed to increase the potential of palm oil as a viable

source for polyols and polyurethane formulations. Olefin metathesis is a very powerful

46

transformation technology adopted by our research group that promises to be one of the

platforms that can be used on palm oil and other vegetable oils to achieve this goal. It is an

important organic synthesis technique that holds exceptional promise in oleochemistry for

many industries. It is already used on TAG oils and fats to produce fine chemicals,

substrates and materials, many of which serve as or are potential petrochemical

replacements [35-38]. Olefin metathesis can increase the molecular diversify and reactivity

of the natural oil, and therefore the potential for its transformation into functional materials.

Olefin metathesis (Scheme 2.1) is a reversible reaction involving the exchange of the

alkylidene groups between the reactant alkene moieties in the presence of catalysts,

typically transition metal complexes [38, 39].

Scheme 2.1. Representation of olefin metathesis reaction.

Olefin metathesis is categorized further as self-metathesis and cross metathesis [36,

38]. In the self-metathesis reaction (forward reaction in Scheme 2.1) the same olefin

molecules react to produce two different olefin products. The self-metathesis of TAGs

results in a complex mixture comprising linear oligomers (from dimer to pentamer),

macrocyclic structures, cross-linked polymers, as well as trans-/cis isomers [40]. In a cross

metathesis reaction (backward reaction in Scheme 2.1) two different olefins are reacted to

produce a new olefin product. Cross-metathesis of a vegetable oil with olefins results in a

metathesized TAG (MTAG) mixture including modified TAG structures, such as terminal

double bonds, not present in the natural oil [41, 42]. The actual composition of a metathesis

product is highly dependent on the reaction conditions, such as starting materials,

47

temperature, type of catalyst, etc., which provides the possibility of controlling the product

composition [43-45].

The cross-metathesis of a TAG oil can be used to produce a feedstock with increased

molecular diversity and reactivity suitable for the production of more functional polyols

and polyurethanes as demonstrated with triolein [20]. The reaction, among other

modifications, shortens some of the unsaturated fatty acids at the location of the double

bond producing low molecular weight metathesized products with terminal double bonds,

offering less steric hindrance and in some cases increased reactivity [39, 46]. Because of

its low molecular weight and terminal double bond structure, the cross metathesized TAG

can produce polyols with terminal hydroxyl groups and therefore polyurethane networks

with dramatically reduced dangling chains [20].

Cross-metathesis reaction of crude palm oil with ethylene produced terminal alkenes

such as: 1-decene and 1-heptene in low yield [47]. Ethylene cross metathesis is one of the

cheapest and most industrially viable techniques for selective transformation of vegetable

oils, but it still has problems related to low yield, poor selectivity and low catalyst turnover

due to complicated reaction pathways [37, 38]. The modified TAG byproduct obtained via

1-butene cross metathesis of palm oil contains similar terminal structures as those from

ethylene cross metathesis, that can be used as valuable materials to produce polyols without

dangling chain. The composition and the properties of the modified palm oil TAG from 1-

butene metathesis have not been fully understood.

The present work reports on the characterisation of the chemistry, structure, and

physical properties of the product of the cross-metathesis of palm oil with 1-butene

48

(butenolysis) stripped from its olefins (referred to in the text by PMTAG) and the synthesis

of polyols from PMTAG. The uniqueness of the structure of the transformed material

compared to the natural oil is highlighted and its potential for the production of value added

products is assessed. Note that high conversion and productive catalyst turnover were

achieved similarly to what was reported with similar synthetic routes, such as 2- butene

cross metathesis of plant oils [48, 49].

PMTAG was provided by our industry partner, Elevence Renewable Sciences (ERS,

Bolingbrook, Ill., USA), who first introduced the technique [50]. It is in fact the by-product

of the industrial biorefinery that produces 1-decene and 3,4-dodecene linear aliphatic

olefins for the fine chemicals sector. ERS currently operate a biorefinery plant in Indonesia

that processes 400 million lbs. of palm oil annually, with advanced plans to build other

biorefinery processing plants in North America that will utilize cross-metathesis on native

plant oils such as soybean oil and canola oil. The transformation of the by-product into

polyols (and other chemicals) as demonstrated has the potential to increase the profitability

of the bio-refineries dramatically.

The polyol was synthesized by the epoxidation of the PMTAG using hydrogen

peroxide (H2O2) and formic acid followed by ring opening reaction with H2O and HClO4.

This is a well-established economical route to produce polyols. In this method the double

bonds are converted into oxirane moieties and the epoxy groups are converted into

hydroxyl groups by ring opening reaction with suitable reagents like HClO4 and H2O to

give the polyol [51]. The reaction parameters (solvents type, time and temperature) were

optimized in order to produce the most economical and functional polyol.

49

The chemical structure and chemical composition of PMTAG and PMTAG Polyol

were determined by 1H-NMR, GC, MS and HPLC. Their thermal degradation, thermal

transformation behavior and flow properties were characterized with TGA, DSC, and

rotational rheometry, respectively.

2.2 Materials and Methods

2.2.1 Materials

PMTAG is one of the products of the cross-metathesis of palm oil and 1-butene

which was stripped of olefins and provided by ERS. Ethanol (anhydrous), toluene,

potassium hydroxide, and sodium thiosulfate were purchased from ACP chemical Inc.

(Montreal, Quebec, Canada) and were used without further treatment. Iodine monochloride

(95%), potassium iodide (99%), and phenolphthalein were purchased from Sigma-Aldrich

Canada Co. (Oakville, Ontario, Canada).

The general materials for PMTAG polyol synthesis were: formic acid (88 wt %),

hydrogen peroxide (H2O2) solution (30 wt %) purchased from Sigma-Aldrich, Canada,

perchloride acid (70%) from Fisher Scientific, Canada, hexanes (Hx), dichloromethane

(DCM), ethyl acetate (EA) and tetrahydrofuran (THF) from ACP chemical Int. (Montreal,

Quebec, Canada). All were used without further treatment.

2.2.2 Chemistry characterization techniques

2.2.2.1 Titrimetric Methods (OH value, Acid value and Iodine value)

Iodine and acid values were determined according to ASTM D5554-95 and ASTM

D4662-08, respectively. Hydroxyl value was determined according to ASTM D1957-86.

50

2.2.2.2 Nuclear magnetic resonance (NMR)

1H-NMR spectra of PMTAG and PMTAG Polyol were recorded in CDCl3 as

solvent on a Varian Unity-INOVA (McKinley Scientific, USA) at 499.695 MHz. The

spectra were obtained using an 8.6 μs pulse with 4 transients collected in 16202 points.

Datasets were zero-filled to 64000 points, and a line broadening of 0.4 Hz was applied

prior to Fourier transformation. Chemical shifts were referenced relative to residual solvent

peaks (7.26 ppm). The spectra were processed using spinwork NMR Processor, version 3.

2.2.2.3 Mass spectrometry (MS)

Electrospray Ionisation Mass Spectrometry (ESI-MS) analysis of PMTAG Polyol

was performed on a QStar XL quadrupole time-of-flight mass spectrometer (AB Sciex,

Concord, ON) equipped with an ionspray source and modified hot source-induced

desolvation (HSID) interface (Ionics, Bolton, ON). The ion source and interface conditions

were adjusted as follows: ionspray voltage (IS) = 4500 V, nebulising gas (GS1) = 45,

curtain gas (GS2) = 45, declustering potential (DP) = 60 V and HSID temperature (T) =

200 C. Multiply-charged ion signals were reconstructed using the BioTools 1.1.5

software.

2.2.2.4 High pressure liquid chromatography (HPLC)

HPLC was performed on an e2695 HPLC system (Waters Corporation, Milford,

MA, USA) fitted with a Waters ELSD 2424 evaporative light scattering detector. The

HPLC was equipped with an inline degasser, a pump and an auto-sampler. The ELSD

nitrogen flow was set at 25 psi with nebulization and drifting tube maintained at 12 ºC and

55 ºC, respectively. Gain was set at 500.

51

A slow method was used for the HPLC analysis of PMTAG. The analysis was

performed with an X-Bridge column (C18, 150mm × 4.6 mm, 5.0 µm, X-Bridge column,

Waters Corporation, MA, and Superspher 100 RP-18, 250mm × 4.0 mm, Thermo

Science)in series with Superspher 100 RP-18 column (250 mm × 4.0 mm, from Thermo

Scientific, Waltham, MA, USA) both at 30 ºC. The sample (4 L) was passed through the

columns by reversed phase in isocratic mode. The mobile phase (2-propanol: acetonitrile:

heptane (38:57:5)v) was run for 120 min at a flow rate of 0.5 ml/min.

For the analysis of PMTAG polyol, a Betasil diol column (250mm × 4.0 mm, 5.0

µm) was used at 50 ºC. The sample (4 L) was run in normal phase and in gradient elution

mode. The mobile phase was started with heptane: ethyl acetate ratio of (90:10)v run for 1

min at a flow rate of 1 mL/min, then (67:33)v in 55 min. The ratio of ethyl acetate was

increased to 100% in 20 min and then held for 10 min.

In both cases, 5 mg/ml (w/v) solution of crude sample in heptane was filtered

through a filter vial 35540 (Thomson Instrument Company, Oceanside, CA). All solvents

were HPLC grade and obtained from VWR International (Mississauga, ON, Canada).

Waters Empower Version 2 software was used for data collection and data analysis. Purity

of eluted samples was determined using the relative peak area.

2.2.2.5 Gas chromatography (GC)

GC of PMTAG was performed by ERS on an Agilent 7890 equipped with a

split/splitless inlet. The splitter was connected to two detectors: a flame ionization detector

(FID) and Agilent 5975C mass selective detector (MSD) via deactivated guard columns.

The length of the guard column to the FID was 0.5 m and 5.0 m to the MSD. The column

52

used for the analysis was a Restek Rtx-65TG capillary column (Crossbond 65% diphenyl

/ 35% dimethyl polysiloxane; 30 m × 0.25 mm × 0.1 µm df). One microliter of the sample

was injected using a LEAP Technologies Combi-PAL autosampler equipped with a 10 µL

syringe.

2.2.3 Physical characterization techniques

2.2.3.1 Thermogravimetric analysis (TGA)

TGA of PMTAG and PMTAG Polyol was carried out on a TGA Q500 (TA

Instruments, DE, USA). Approximately 8.0 – 15.0 mg of sample was loaded in the open

TGA platinum pan. The sample was equilibrated at 25 °C and then heated to 600 °C at a

constant rate of 10 °C/min. The TGA measurements were performed under dry nitrogen of

40 mL/min for balance purge flow and 60 mL/min for sample purge flow.

2.2.3.2 Differential Scanning Calorimetry (DSC)

DSC measurements of PMTAG and PMTAG Polyol were performed in the

standard mode on a Q200 model (TA Instruments) under a nitrogen flow of 50 mL/min.

The sample (3.5 to 6.5 ± 0.1 mg) in hermetically sealed aluminum DSC pans was

equilibrated at 90 °C for 10 min to erase thermal memory, and then cooled at a constant

rate (5.0 °C/min) to -90 °C where it was held isothermally for 5 min, and subsequently

reheated at 5.0 °C/min to 90 °C.

“TA Universal Analysis” software was used to analyze the TGA and DSC data and

extract the crystallization and melting characteristics. Non-resolved peaks were analyzed

with the help of the first and second derivatives of the differential heat flow. The

measurement temperatures are reported to a certainty of better than ± 0.5 °C.

53

2.2.3.3 Rheology

The flow behavior and viscosity versus temperature of PMTAG and PMTAG

Polyol were measured on a temperature controlled Rheometer (AR2000ex) using a 40-mm,

2° steel geometry. Temperature control was achieved by Peltier attachment with an

accuracy of ~0.2 °C. Shear stress versus shear rate curves were measured at 10 °C intervals

from high temperature (100 °C) to ~ 10 °C below the DSC onset of crystallization

temperature. The range of shear rates (1 - 2000 s-1) was optimized for torque (lowest

possible is 10 μNm) and velocity (maximum suggested of 40 rad/s). The viscosity versus

temperature data were collected at constant shear rate (200 s-1) using the ramp procedure

while the sample was cooling (1.0 °C/min) from ~110 °C to just above the crystallization

point. Data points were collected at intervals of 1 °C.

The shear rate – shear stress curves were fitted with the Herschel-Bulkley equation

(Eq. 2.1), a model commonly used to describe the general flow behavior of liquid materials,

including those characterized by a yield stress.

0

nK Eq. 2.1

Where denotes the shear stress, 0 is the yield stress below which there is no

flow, K the consistency index and n the power index. n depends on constitutive

properties of the material. For Newtonian fluids n = 1, shear thickening fluids, 1n and

for shear thinning fluids, 1n .

The experimental viscosity – temperature data were analyzed using a generalized form

of the van Velzen expression (GvVE, Eq. 2.2).

54

1

ln 1m

AT

Eq. 2.2

The GvVE yields parameters which are physically meaningful; its parameter A relates

directly to the magnitude of the viscosity of the liquid and its exponent m is related to the

complexity of the molecule similar to the parameters of the Andrade and generalized

Andrade models [52]. The goodness of fit was determined using the percent relative

deviation (RD%), referred to herein as residuals (Eq. 2.3).

exp

exp

% 100cal

RD

Eq. 2.3

Where exp and cal are the experimental and calculated viscosities, respectively.

2.3 Results and Discussion

2.3.1 Chemical Characterization of PMTAG

The acid value of PMTAG was less than 1 mg KOH/g, indicating a very low free

fatty acid content. The degree of unsaturation of PMTAG as evaluated by its iodine value

(IV = 52) was higher compared to the starting palm oil (IV= 45), attributed to the overall

lower molecular weight of its unsaturated TAGs. Note that the IV of PMTAG is also higher

than any highly saturated vegetable oil such as coconut oil (IV: 7-10) and palm kernel oil

(IV: 16-19), but much lower than that of the highly unsaturated vegetable oils such as:

soybean oil (IV: 120-136), sunflower oil (IV: 125-144), linseed oil (IV: 136-178), olive oil

(IV: 80-88), tung oil (IV: 163-173), and grape seed oil (IV: 124-143) [53].

55

2.3.2 Compositional Analysis of PMTAG

The compositional analysis of PMTAG was performed using 1H-NMR, GC and

HPLC. Because of its very low free fatty acid content, the fatty acid and TAG profiles of

PMTAG were determined assuming that only TAG structures were present. PMTAG

would naturally comprise all possible transformations of its unsaturated TAGs and all non-

transformed saturated TAGs. The general structures of the transformed TAG can be

described with a model cross metathesis reaction of 1-butene and triolein (OOO) (see

Scheme 2.2). The TAG structures in PMTAG as inferred from all possible transformations

based on this ideal system are shown in Scheme 2.3. The TAG profile of palm oil and

corresponding modified TAG in PMTAG are presented in Table 2.1.

Scheme 2.2. Metathesis reaction of triolein with 1-butene. n=0, the fatty acid is 9-

denenoic acid (D), n= 2, the fatty acid is 9-dodecenoic acid (Dd), and n= 8, the fatty acid

is oleic acid (O).

56

Scheme 2.3. Possible TAG structures composing PMTAG. n=0, 2, 8; m= 11 to 20.

Table 2.1. TAG profile of palm oil and corresponding modified TAG in PMTAG.

TAG Content

(wt%) Potential PMTAG composition

Tri-

unsaturated

OLL 0.2-0.9 ODD, DDD, DDDd, DDdDd, OLL, OLO, OOO,

OLD, OLDd, OOD, ODD, ODDd, ODdDd, LDD,

LDDd, LDdDd, DdDdDd, and their isomers OLO 1.3-2.3

OOO 3.3-6.6

Bi-

unsaturated

POL 9.0-11.2 POL, POO, PDD, POD, PDDd, PODd, PDdDd

and their isomers POO 20.5-26.2

SOO 1-3.6 SOO, SDD, SOD, SDDd, SODd, SDdDd and their

isomers

PLL 1.3-3.4 PLL, PDD, PLD, PDDd, PLDd, PDdDd and their

isomers

Mono-

unsaturated

POP 27.1-31.0 POP, PDP, PDdP

SOS 0.1-1.4 SOS, SDS, SDdS

POS 4.6-5.9 POS, PDS, PDdS

PLP 6.5-11.0 PLP, PDP, PDdP

MLP 0.2-1.0 MLP, MDP, MDdP

Saturated

PPP 0.7-7.2 PPP

PPM 0.6-9.8 PPM

PPS 0.1-1.8 PPS

D: 9-decenoic acid; Dd: 9-dodecenioc acid; M, myristic acid; O, oleic acid; P,

palmitic acid; L, linoleic acid; S, stearic acid. DDD: 1,2,3-triyl tris(dec-9-enoate), DDS:

3-(dec-9-enoyloxy) propane-1, 2-diyl distearate, and DSS: 3-(stearoyloxy) propane-1, 2-

diyl bis(dec-9-enoate).

57

2.3.2.1 GC results of methylated PMTAG

The fatty acid composition of PMTAG as determined by GC of methylated

PMTAG is presented in Table 2.2. The GC results indicate that PMTAG was comprised

of ~46 mol% unsaturated fatty acids and ~54 mol% saturated fatty acids. The decenoic acid

(C10:1) and 9,12 tridecenoic acid (C13:2) are the terminal double bonded fatty acids

resulting from the shortening of oleic acid and linoleic acid, respectively. Dodecenoic acid

(C12:1) and 9,12-pentadecenoic acid (C15:2) are non-terminal double bonds formed by the

exchange of the oleic acid and C13:2 with 1-butene, respectively. As expected, the

saturated fatty acids in PMTAG matched those of the natural oil. Note that the amount of

linoleic acid (C18:2) that was detected in PMTAG was very small and would not impact

its properties.

Table 2.2. GC results of methylated PMTAG.

UFAa C10:1 C12:1 C13:2 C15:1 C15:2 C18:1 C18:2

Wt.% 17.52 11.45 0.91 0.58 0.51 5.77 0.17

Mol% 10.30 6.58 0.44 0.24 0.24 2.10 0.06

SFAb C12:0 C14:0 C16:0 C18:0 C20:0 C21:0 Others

Wt.% 0.31 1.24 50.35 9.28 0.35 0.12 1.28

Mol% 0.16 0.54 19.67 3.30 0.12 0.04

aUFA: unsaturated fatty acids: decenoic acid (D, C10:1), dodecenoic acid (Dd,

C12:1), 9,12 tridecenoic acid (C13:2) 9-pentadecenoic acid (C15:1), 9,12-pentadecenoic

acid (C15:2), oleic acid (O, C18:1), linoleic acid (L, C18:2)

bSFA: saturated fatty acids: palmitic acid (P, C16:0), Lauric acid (L, C12:0), Myristic

acid (M, C14:0), stearic acid (S, C18:0), Arachidic acid (A, C20:0)

58

2.3.2.2 1H-NMR of PMTAG

The 1H-NMR spectrum of PMTAG is shown in Figure 2.1. For clarity, the

spectrum is split into two panels: 1a and 1b for the δ 2.5-0.7 ppm and δ 6.0-4.0 ppm

chemical shift ranges, respectively. The corresponding 1H-NMR data are provided in the

Appendix (Table A1). The chemical shifts were attributed according to [54].

(a) (b)

Figure 2.1. 1H-NMR of PMTAG. (a) Chemical shift range between δ 2.5 and 0.7

ppm, (b) Chemical shift range between δ 6.0 and 4.0 ppm

The -CH2CH(O)CH2- and -OCH2CHCH2O- protons of the glycerol skeleton of the

TAG structure were distinctly presented at δ 5.3-5.2 ppm and 4.4-4.1 ppm, respectively.

Two kinds of double bonds were detected: (1) terminal double bonds (n= 0 in Scheme 2.3),

-CH=CH2 and –CH=CH2 at δ 5.8 ppm and 5.0 to 4.9 ppm, respectively, and (2) internal

double bonds (n≠ 0 in Scheme 2.3), -CH=CH- at δ 5.5-5.3 ppm. The α-H to ester group -

C(=O)CH2- was presented at δ 2.33-2.28 ppm, α-H to -CH=CH- was presented at δ 2.03-

1.98 ppm, and β-methylene proton (-C(=O)CH2CH2-) was presented at δ 1.60 ppm. Also,

two kinds of –CH3 were detected, one at 1.0-;0.9 ppm (n= 2 in Scheme 2.3), and another

at 0.9-0.8 ppm (n= 8 in Scheme 2.3). The signature peak of the proton between two double

59

bonds (the chemical shift at 2.6-2.8 ppm) indicative of polyunsaturated fatty acids was not

presented by 1H-NMR of PMTAG.

1H-NMR analysis confirmed that the metathesis reaction did not alter the overall

saturation profile inherited from the starting palm oil but dramatically modified the

configuration and structure of the unsaturated TAGs. The relative amounts of saturated

fatty acids, terminal and internal double bond structures of the PMTAG, as evaluated based

on the relative area under their characteristic 1H-NMR peaks are presented in Table 2.3.

Note that the terminal double bond (mol%), internal double bond RTDB (mol%) and

saturated fatty acid (mol%) were calculated based on the integrated protons under 5.0 to

4.9 ppm, δ 5.5-5.3 ppm and 1.0-0.8 ppm respectively. These data indicate that PMTAG

was constituted of approximately ~50% saturated and ~50% unsaturated fatty acids, half

of which were terminal double bonds (n=0 in Scheme 2.3). The internal double bonds (n≠

0 in Scheme 2.3) contain trans-(δ 5.38-5.34 ppm) and cis (δ 5.33-5.30 ppm)-configurations

with a trans-/cis- ratio of ~2:1.

Table 2.3. Relative amounts of saturated and unsaturated structures in PMTAG as

determined by 1H-NMR.

Fatty Acids Structure Content

(mol %)

Unsaturated

Terminal double

bond

–CH=CH2

–CH=CHCH2CH=CH2 24.9

Internal double

bond

–CH=CHCH2CH3

–CH=CHCH2CH2CH2CH2CH3

–CH=CHCH2CH2CH2CH2CH2CH2CH2CH2CH3

–CH=CHCH2CH=CHCH2CH2CH2CH2CH2CH3

–CH=CHCH2CH=CHCH2CH3

28.4

Saturated 46.7

60

2.3.2.3 HPLC results of PMTAG

The HPLC curves of PMTAG recorded using the method described in Section 2.2.1

are shown in Figure 2.2. The corresponding HPLC data are reported in Table 2.4. The

analysis of the HPLC of PMTAG was carried out with the help of purified DDD, DDS and

DSS used as reference standards, which was synthesized and characterized in our

laboratory. These TAGs are representatives of tri-unsaturated, di-unsaturated and

monounsaturated TAGs that result from 1-butene cross metathesis of palm oil.

Figure 2.2. HPLC of PMTAG (solid line) superimposed with the HPLC of DDD,

DDS and DSS. The standard TAGs are indicated at the side of their HPLC trace (dashed

lines)

As shown in Figure 2.2, an excellent separation of the HPLC peaks was obtained for

PMTAG. Figure 2.2 shows three main groups of HPLC peaks delineated by the elution

Time (min)

0 20 40 60 80 100

LS

U

0

30

60

90

120

200

300

DS

S

DD

D

DD

S

61

times of DDD, DDS and DSS. This indicates the presence of three groups of molecules:

(1) the triunsaturated TAGs showing before DDS, (2) TAGs with two unsaturated moieties

(shortened or not) and those with shortened single unsaturated moiety showing after DDD

up to DSS, and (3) the non-shortened monounsaturated and saturated TAGs showing after

DSS (retention times higher than 52 min). The area % from the HPLC chromatogram of

each peak is presented in Table 2.4. The individual peaks can be assigned more specifically

with the help of the trend in elution time reported in the literature for TAG standards [55].

The TAGs were shown to usually elute successively from MMM (trimyristoylglycerol) to

SOS (1,3-distearoyl-2-oleoyl-sn-glycerol) according to molecular weight and saturation

level in the order MMM, MMP (1,2-dimyristoyl-3-palmitoyl-sn-glycerol), PPM (1,2-

dipalmitoyl-3- myristoyl -sn-glycerol), OOO (Triolein), OOP (1,2-dioleoyl-3-palmitoyl-

sn- glycerol), PPO (1,2-dipalmitoyl-3- oleoyl -sn-glycerol), PPP (tripalmitoylglycerol),

OOS (1,2-dioleoyl-3-stearoyl-sn- glycerol), POS (1-palmitoy-l,2-oleoyl,3-stearoyl-sn-

glycerol) and SOS. DDD eluted first (at ~10.4 min in Figure 2.2) because it has the lowest

molecular weight and highest unsaturation. The group of HPLC peaks that are closest to

DDD are attributable to the highly unsaturated and low molecular weight TAGs. DDD was

followed successively by the triunsaturated TAGS, like DDDd, DDdDd, DdDdDd, DDO,

DDL etc. and their isomers, at retention times between 11 and 18 min. These were followed

by the diunsaturated TAGs having the formula DDX (where X=P, M) before DDS (19.9

min). The diunsaturated molecules with structures like XDDd, XDdDd, XOD, XODd (X=

S, P etc.) and their isomers eluted after DDS at retention time between 20 and 32 min. DXX

and DdXX type of TAG structures (X= P, M) may possibly have eluted before DSS

between 40-50 min. According to the succession criteria established using [55], DSS was

62

followed by DdSS, POS, PPS, SOS and their isomers between 51 and 80 min. The low

molecular weight saturated TAG PPP and PPM may have possibly eluted between the

triunsaturated and diunsaturated TAGs.

Table 2.4. HPLC analysis data of PMTAG.

Peak RT (min) Area (%) Structure

1 10.4 0.16 DDD

2 11.2 0.71 --

3 11.4 0.20 --

4 17.1 10.5 --

5 19.7 0.59 --

6 19.9 11.8 DDS

7 21.7 0.45 --

8 23.3 0.17 --

9 23.9 1.07 --

10 28.2 0.10 --

11 32.6 1.42 --

12 34.3 42.4 --

13 39.7 0.54 --

14 42.0 16.6 --

15 51.8 0.33 DSS

16 74.5 1.86 --

17 79.8 11.2 --

2.3.3 Physical Properties of PMTAG

2.3.3.1 Thermogravimetric Analysis of PMTAG

The TGA and DTG profiles of PMTAG are shown in Figure 2.3. The DTG curve

presented a single peak at ~399 °C indicating a one-step degradation process that is

generally associated with the breakage of the ester bonds [56]. Note however that the DTG

presented an asymmetrical low temperature wing that suggests that some evaporation has

occurred before degradation. Such evaporation is possible due to the presence of low

molecular weight molecules in the PMTAG.

63

Figure 2.3: TGA and DTG profiles of the PMTAG.

The temperature of degradation determined at 1%, 5% and 10% weight loss ( 1%T ,

5%T and 10%T , respectively) were ~260 °C, 310 °C and 330 °C, respectively. These values

are ~20 °C lower than those measured for palm oil [57], probably due to the recording of

the volatilisation of the low molecular weight components of PMTAG. The onset of

thermal degradation ( onT ) of PMTAG as defined by the intersection of the zero weight loss

baseline with the tangent at the inflection point of the TGA curve, was at 339 °C, a

relatively lower temperature than the 347 °C reported for palm oil [57]. However, the DTG

peak temperature of PMTAG (~399 °C) is relatively higher than what was recorded for

palm oil (381 °C) [57]. This indicates that although generally starting to degrade at lower

temperature, the rate of degradation of PMTAG reaches its maximum at a higher

temperature because of its modified structures.

2.3.3.2 Thermal transition behavior

The DSC thermograms obtained during cooling and subsequent heating of PMTAG

(both at 5 °C/min) are presented in Figure 2.4a and 2.4b, respectively. The corresponding

Temperature (oC)

100 200 300 400 500

We

igh

t L

oss

(%

)

0

20

40

60

80

100

DT

G

/%oC

-1

TGA

DTG

64

characteristic temperatures (onset, onT , offset, offT , and peak temperatures, pT ) are listed

in Table 2.8. The cooling thermograms presented relatively well-separated thermal events

(P1, P2 and P3 in Figure 2.4a). Each exotherm is attributable to overlapping peaks due to

molecules with close enough structural features to crystallize in well-defined and separated

ranges of temperatures [58]. This indicates that the molecules of PMTAG form specific

groups which form well-defined melting portions.

The DSC heating thermogram of PMTAG was more complex than its crystallization

counterpart. For example, as many as eight endotherms and two prominent exotherms (at

= 19.3 and 2.9 ºC in Figure 2.4b) were observed in the heating trace of PMTAG. Despite

the polymorphic transformations that occurred, one can still distinguish two group of

endotherms separated at about 30 °C (G1 and G2 in Figure 2.4b) that can be correlated to

the two groups of exotherms observed during crystallization (G1 and G2 in Figure 2.4a)

indicating two distinct PMTAG portions, one melting above room temperature and the

other below room temperature.

Figure 2.4: (a) Crystallization thermograms of PMTAG obtained (b) corresponding

heating profiles (both at 5 °C/min)

-15 0 15 30 45

0.2

0.4

0.6

0.8

1.0(a)

P1

P2

P3

Temperature (oC)

Heat

Flo

w (

Wg

-1)

(

Exo u

p)

G2

G1

-30 -15 0 15 30 45 60

-0.6

-0.4

-0.2

0.0

G1

G2

Temperature (oC)

He

at

Flo

w (

Wg

-1)

(

En

do

do

wn

)

(b)

65

The DSC profile of PMTAG bare close similarity with the profile of the natural

palm oil. The low and high melting portions of PMTAG are reminiscent of the stearin and

olein fractions of palm oil [59]. Therefore, comparably to palm oil and for convenience,

the thermal events that appeared above room temperature (G1 in Figure 2.4a and 2.4b) are

associated with a stearin-like portion of PMTAG, and the thermal events that appeared

below room temperature and at sub-zero temperatures (G2 in Figure 2.4a and 2.4b) are

associated with an olein-like portion of PMTAG. Obviously, the portion represented by the

DSC above 30 C is constituted by the highly saturated and trans- configuration species of

PMTAG, so-called stearin portion, and the portion represented by the DSC below 30 C is

constituted by its highly unsaturated and short length species, so-called olein portion. The

relative enthalpy of crystallization estimated for the stearin (G1) and olein (G2) portions

was 25 % and 75 %, respectively, of the total enthalpy. The melting enthalpy of the stearin

and olein portions represent 23% and 77% of the total enthalpy, respectively, correlating

very well with what was obtained with the enthalpy of crystallization.

The compositional analysis of the two portions can be attempted based on the

composition of PMTAG (Section 3.2) and with the help of previous knowledge of the

crystallization trends observed by DSC for natural TAGs [60]. It is commonly known that

saturated TAGs crystallize at higher temperature than monounsaturated TAGs followed by

diunsaturated TAG and finally triunsaturated TAGs. Symmetrical TAGs crystallize at

higher temperatures than their asymmetrical counterparts. Also for a given level of

saturation, crystallization temperature is higher for higher mass TAGs. The saturated TAGs

like: PPP, MMP and MMM, are known to crystallize above ambient followed by the

66

monounsaturated TAGs such as SOS, POS and PPO, which crystallize below room

temperature, typically above freezing temperature. The diunsaturated TAGs like POO,

OPO, OSO and SOO crystallize at lower temperature which could be as low as ~-22 ºC in

the case of POO, for example [60]. The tri-unsaturated TAGs such as OOO show a single

exotherm at even much lower temperature [60]. The triunsaturated DDD and the

diunsaturated DDS standards, displayed two exotherms each, at ~-40 °C and ~-30 °C, and

at ~ -3 °C, ~ -15 °C, respectively, which fall in the range of temperature of the olein portion

of PMTAG. The monosaturated DSS standard displayed a crystallization peak at ~ 30 °C

and a shoulder at ~25 °C, which indicates that it belongs to the stearin fraction of PMTAG.

Therefore, the exotherm observed at ~32 °C (P1 in Figure 2.4a) is associated with the

highly saturated/trans components of PMTAG and the peak at ~12 °C (P2 in Figure 2.4a)

is related to the mono-unsaturated and di-unsaturated TAGs. The peak at -11 °C (P3 in

Figure 2.4a) is related to the TAGs with the lowest molecular mass and the most

unsaturated tri-unsaturated TAGs.

2.3.3.3 Flow behavior and viscosity of the PMTAG

Selected shear stress versus shear rate curves recorded for PMTAG between 30 ºC

and 100 ºC are shown in Figure 2.5. Fits to the Herschel-Bulkley model (Eq. 2.1) are

included in the figure (dashed lines in Figure 2.5). Evident from Figure 2.5, share rate –

shear stress curves were linear for the whole shear rates range, except at 30 ºC where it was

linear below 150 s-1 only. Application of Eq. 1 generated power index values ( n ) equal to

unity and no yield stress (straight lines in Figure 2.5, R2> 0.99999), indicating a Newtonian

behavior. The deviation from the Newtonian behavior above 150 s-1 at 30 °C is due to the

close proximity of this temperature to the crystallization onset of PMTAG.

67

Figure 2.5: Shear rate versus shear stress of the PMTAG

Viscosity versus temperature curves of PMTAG are presented in Figure 2.6. The

exponential behavior of these curves is typical of liquid hydrocarbons [61, 62]. The

experimental data collected above 30 °C, a temperature corresponding to the onset of

crystallization, was fitted very well with the generalized van Velzen equation (Eq. 2.2) with

residuals of less than 1% (RD% in the lower panel of Figure 2.6). Below 30 °C, the RD%

(Eq. 2.3) is higher than 1% and increases exponentially with decreasing temperature. This

cut-off is the temperature at which the flow behavior started to depart from Newtonian to

shear thickening at high shear rate (curve 30 C in Figure 2.5) because PMTAG was

crystallizing. The PMTAG was probably forming liquid-crystal or gel-like states below 30

°C.

Shear Rate (s-1

)

0 200 400 600 800 1000 1200

Shear

Str

ess

(Pa)

0

10

20

30

40

50

40

50

T (oC)

60

70

80

90

30

(a)

68

Figure 2.6: Viscosity versus temperature of PMTAG. Dotted lines are fit to the generalized

van Velzen equation (eq.2). The lower panel represents the residuals in % (RD%) versus

temperature.

The viscosity of liquid PMTAG is only slightly lower than that of palm oil [63] and

falls in the range of the highly unsaturated vegetable oils such as soybean oil, sunflower

oil, high oleic sunflower oil, and corn oil [64]. The key elements that brought the viscosity

of PMTAG closer to that of the highly unsaturated vegetable oils were chiefly the

modifications to the molecular mass (molecular mass decreased) introduced by the

metathesis reaction. Importantly, these levels of viscosity will allow for the handling and

processing techniques and equipment in the existing various applications such as the

synthesis of monomers for polymers, fuel and lubricants to be used for PMTAG.

2.3.4 Synthesis of PMTAG Polyol

PMTAG Polyol was prepared from PMTAG in a two-step reaction as described in

Scheme 2.4: (i) epoxidation of the PMTAG by hydrogen peroxide (H2O2) and formic acid

Vis

co

sity (

Pa

.s)

0.02

0.04

0.06

0.08

0.101

oC/min

(b)

20 40 60 80 100 120

RD

/%

-5.0

-2.5

0.0

2.5

5.0

Temperature (oC)

69

(HCOOH), followed by (ii) hydroxylation using HClO4 as a catalyst. The reaction progress

was monitored by TLC and 1H-NMR. The products were analyzed with HPLC and 1H-

NMR.

Scheme 2.4. Synthesis of PMTAG Polyol (n=0, 2, 8; m=11 to 20)

2.3.4.1 Optimization of the Synthesis of PMTAG Polyol

The epoxidation reaction was performed in different media (DCM, EA, THF and

without solvent) and optimised for reactants content (formic acid, and hydrogen peroxide),

time and temperature of the reaction. The effort was targeted at achieving the most

conversion of unsaturation sites into epoxides. The hydroxylation reactions were conducted

at room temperature in THF as well as in water. The ratio of the epoxy PMTAG to HClO4

and the reaction time was varied in order to optimize the cost of the polyol. The details of

the epoxidation and hydroxylation reactions are presented in Table 2.5.

70

The epoxidation of PMTAG using a ratio of PMTAG: Formic acid: H2O2 of 1: 1: 1.4

was effective and complete when it was run with DCM as the solvent (E1). 1H-NMR of the

epoxidized PMTAG of this experiment is shown in Figure 2.7. There were no chemical

shifts related to double bonds (at 5.8, 5.4 and 5.0 ppm) indicating their complete conversion

into epoxides. The chemical shifts of internal epoxy rings were presented at δ 2.9 - 2.7 ppm

and those of terminal epoxy rings at δ 2.7 - 2.4 ppm. The chemical shift due to the protons

-CH2CH(O)CH2- and -OCH2CHCH2O- of the glycerol skeleton (at δ 5.3-5.2 ppm and 4.4-

4.1 ppm, respectively), -C(=O)CH2- (at δ 2.33-2.28 ppm), α-H to -CH=CH- (at δ 2.03-1.98

ppm), and -C(=O)CH2CH2- (at δ 1.60 ppm) indicate that the TAG-like glycerol backbone

structure was preserved.

When epoxidation was conducted in THF (E4), or EA (E5) or without solvent (E6 and

E7), the epoxidation did not complete due to partial miscibility of the reactants in these

experiments. The 1H-NMR data of the epoxy of these experiments (Figures. A1, A2 and

A3 in the Appendix), specifically the relative areas of the δ 5 ppm to 4.8 ppm characteristic

of the terminal double bonds indicate that more than 60% of the terminal double bonds of

PMTAG were not epoxidized. Also a PMTAG Polyol by-product having a formic acid unit

attached to the TAG was detected (characteristic peak at δ ~8ppm in Figures. A1 and A2)

in the product of epoxidation with EA (E5) and the dry epoxidation (E6 and E7). The

structure of the formylated polyols is provided in Scheme A1 in the Appendix). Note that

even with DCM as the solvent, the reduction of formic acid and hydrogen peroxide

concentration in E2 and E3 resulted in an incomplete epoxidation by leaving more than

40% terminal bonds. A complete conversion of unsaturation of PMTAG into the

71

corresponding epoxide in DCM occurred at 1/ 1/ 1.4 ratio by weight of PMTAG, HCOOH

and H2O2, respectively.

Figure 2.7. 1H-NMR spectrum of epoxy PMTAG

The epoxidized PMTAG obtained in E1 was deemed the most suitable to make the

best polyol and chosen for the hydroxylation step because all its double bonds were

converted into epoxides. The hydroxylation of epoxy E1 was carried out at room

temperature in a 3:2 mixture of THF: water. The hydroxylation reaction was optimized for

perchloric acid in three experiments (H1-3 in Table 2.5). As expected, the concentration

of perchloric acid affected both acid value and hydroxyl number of the resulting polyol

strongly. With an HClO4: PMTAG weight ratio of 1:1 (H1 in Table 2.5), the reaction

yielded a polyol (Polyol H1) having a large acid value (> 50 ±5 mg KOH/g) and a relatively

small OH number (120 ±5 mg KOH/g). This was a clear indication of a partial hydrolysis

of the TAG esters. When the HClO4 : PMTAG weight ratio was reduced to 0.1:1 and 0.05:1

(H2 and H3, respectively, in Table 2.5), the reaction yielded polyols (Polyol H2 and H3,

C(O)CH(CH2)7CH3

C(O)CHCH2CH3

-OOCCH2CH2-

-OOCCH2-

72

respectively) with similar acid value of ~2 ±1 mg KOH/g and OH number of 155 ±5 mg

KOH/g.

Table 2.5. Optimization data for the synthesis of PMTAG Polyola

Step Solventb PMTAG/Formic

acid/H2O2 T (°C)

Time

(h) Notes

Epoxid

atio

n

E1

DCM

1/ 1/ 1.4 50 48 Complete;

No by-products formed

E2 1/ 0.3/ 1 50 72 Not complete; > 40% terminal

double bonds remained

E3 1/ 0.2/ 1 50

>1

week

E4 THF 1/ 1/ 1.4 50 72 Not complete; > 60% terminal


Formation of by-products E5 EA 1/ 1/ 1.4 50 72

E6

WO 1/ 1/ 1.4

50 72 Not complete, >60% terminal


by products formed at 100 °C

70 72

100 72

E7 100 24

Set temperature was 60 C then

self-heated to 100 C

No double bond detected;

Formic ester polyol was formed

Hydro

xyla

ti

on

Epoxy

PMTAG/HClO4

Time

(h)

Polyol

name

Acid value

(mg KOH/g)

OH number (mg

KOH/g)

H1 THF

+

H2O

1/ 1 20 Polyol H1 >50 ~120

H2 1/ 0.1 48 Polyol H2 ~6 ~150

H3 1/ 0.05 48 Polyol H3 ~2 ~155

aE1 – 7: Epoxidation experiments; H1 – 3: hydroxylation experiments

bEA: Ethyl acetate; DCM: dichloromethane; THF: tetrahydrofuran; WO: without

solvent.

cListed ratio for the starting materials is based on 30% H2O2 solution and 88%

formic acid solution.

Polyol of H2 presented the same NMR as Polyol of H3

The acid and OH value of these polyols were explained in light of their chemical

structures as revealed by 1H-NMR. Polyols H2 and H3 presented practically the same 1H-

73

NMR (Figure 2.8a), explaining the similarity in their physical properties. In both cases,

the 1H-NMR presented the peak at δ 3.8-3.4 ppm characteristic of the –OH groups but not

the peak of the epoxides at (δ) 2.8-2.4 ppm indicating that conversion to hydroxyl groups

was complete. Polyol H2 and Polyol H3 exhibited the chemical shifts of methylene at δ

5.27 ppm and 4.2-4.0 ppm, and methine protons at δ 4.4-4.2 ppm (Figure 2.8a) typical of

TAG glycerol backbones. Furthermore, the peaks at 4.2-4.0 ppm, and 4.4-4.2 ppm of the

methine protons presented a ratio of 1:1 indicative of the integrity of the TAG backbone

and confirming that the hydrolysis of the TAG did not occur for Polyol H2 and Polyol H3.

The 1H-NMR spectrum of Polyol H1 (Figure 2.8b) presented the typical chemical shifts

of the OH groups and showed the chemical shifts of the TAG structure but unlike Polyol

H2 and Polyol H3 did not present the 1:1 ratio of the methine protons at 4.2-4.0 ppm and

4.4-4.2 ppm an evidence of partial hydrolysis.

Figure 2.8. 1H-NMR of (a) PMTAG Polyol H1and (b) PMTAG Polyol H2 and H3

C(O)CH(CH2)7CH3

C(O)CHCH2CH3

-OOCCH2-

74

2.3.4.2 Standard synthesis procedure

The most economical procedure that yielded a polyol with the lowest acid value

and highest OH number, i.e., Polyol H3, was chosen as the standard method to make the

polyol from PMTAG. It is heretofore simple referred to as PMTAG Polyol. Note, however,

that methods of Table 2.5 may be used to custom-produce polyols that would satisfactorily

meet requirements for target polyurethane products.

2.3.4.3 Standard epoxidation procedure

Formic acid (88%; 200g) was added to a solution of PMTAG (200 g) in DCM (240

mL). The mixture was cooled to 0 °C in an ice bath and hydrogen peroxide (30 %, 280 g)

was added drop wise while stirring with a mechanical stirrer (500 to 600 rpm). After the

addition of hydrogen peroxide, the mixture was raised to 50 °C and kept at this temperature

with stirring until the reaction was complete. The reaction was monitored by a combination

of TLC and 1H-NMR and was deemed complete after 48 h. The reaction mixture was then

diluted with 250 mL of DCM, washed with water (200 mL × 2), and then with saturated

sodium hydrogen carbonate (200 mL × 2), and again with water (200 mL × 2). The resulting

epoxy PMTAG product was rotary evaporated to remove the solvent, and then was dried

over anhydrous sodium sulphate.

2.3.4.4 Standard hydroxylation procedure

Approximately 200 g of crude epoxy PMTAG was dissolved at room temperature in a

500 mL mixture of THF/H2O (3:2) containing 14.5 g of perchloric acid. The resultant

mixture was stirred at room temperature for 36 h, a time after which the reaction which

was monitored by a combination of TLC and 1H-NMR was deemed complete. The reaction

mixture was poured into 240 mL water and extracted with CH2Cl2 (2×240 mL). The

75

organic phase was washed with water (2 × 240 mL), followed by 5% aqueous NaHCO3 (2

× 200 mL), and then with water again (2 × 240 mL), and then dried over Na2SO4. After

removing the drying agent by filtration, the solvent was removed with a rotary evaporator

and further dried by vacuum overnight, giving a light yellow grease-like solid.

2.3.5 Compositional analysis of PMTAG Polyol

PMTAG Polyol was fractionated by flash chromatography using a mixture of ethyl

acetate and hexanes as eluent (ratio EA: Hx from 1:6 to 1:2). Since PMTAG Polyol is a

complex mixture of diols, tetrols and hexols with similar polarities, it is very difficult to

separate the individual molecules with 100% purity. However, the chromatographic

seperation yielded groups of polyols (fractions), which helps to explain the composition of

the PMTAG Polyol. Eight (8) fractions were collected and were characterized by 1H-NMR,

MS and HPLC. The 1H-NMR, MS and HPLC data are presented in Table 2.6. The

structures of PMTAG Polyol present in the polyol fractions determined based on MS and

1H-NMR are provided in the Appendix Scheme A2.

2.3.5.1 1H-NMR and MS Results

The 1H-NMR spectrum of Fraction 1 indicated saturated TAG structures only. It

presented the chemical shift of a glycerol skeleton (at δ 5.3 - 5.2 ppm and 4.4 - 4.1 ppm

related to -CH2CH(O)CH2- and -OCH2CHCH2O- protons, respectively) but not the peaks

related to proton neighbored by hydroxyl groups (at δ 3.8-3.4 ppm), or terminal (at δ 5.8

ppm, 5.0-4.9 ppm) and internal double bonds (δ 5.5-5.3 ppm). Fraction 2 and Fraction 3

comprised the hydrolyzed products with no TAG backbone of the PMTAG polyol. Fraction

4 (C53H102O8·H2O) and Fraction 5 (C52H100O8·2H2O) are PMTAG diols derived of oleic

acid (Scheme 2.5a). Fraction 6 was a mixture of PMTAG diols derived from oleic acid and

76

9-dodecenoic acid of PMTAG (Scheme 2.5a and 2.5b, respectively). Fraction 7 was a

mixture of PMTAG diols and tetrols derived from oleic acid, 9-dodecenoic acid and 9-

decenoic acid (Scheme 2.5a, 2.5b and 2.5c, respectively). Fraction 8 was a mixture of

PMTAG diols, PMTAG tetrols and PMTAG hexols derived from the diols of oleic, 9-

dodecenoic and 9- decenoic acids. The relative amount of hexols, tetrols and diols with

terminal hydroxyl groups in PMTAG polyol, as estimated by 1H-NMR was ~24.1%. This

value is consistent with initial terminal double bonds composing PMTAG.

Scheme 2.5. Diol structures produced from oleic acid, 9-dodecenoic acid and 9-

decenoic acid present in the PMTAG as a result of epoxidation followed by hydroxylation.

Table 2.6. Characterization of PMTAG Polyol fractions

1H-NMR Chemical shifts a MS Formula Structure b

F1

5.2 (1H, m), 4.4-4.2 (2H,

dd)), 4.2-40 (2H, dd), 2.4-

2.2 (6H, t), 1.6-1.5 (6H, m),

1.2 (69H, m), 0.8 (9H, t)

947.8 C61H118O6

Saturated TAGs

849.8 C54H104O6

F2

4.4-4.0 (5H, m), 2.4-2.2

(4H, m), 1.6 (4H, m), 1.2

(40H, m), 0.8 (6H, t)

667.5 C42H82O5

Not a TAG structure;

Contains hydrolyzed by-

products

a) Oleic acid-like diol:

b) 9-dodecenoic acid-like diol:

c) 9-decenoic acid-like diol:

77

F3

5.2 (0.1H, m), 4.4-4.0

(2.4H, m), 3.6 (1H, t), 2.4-

2.2 (3H, t), 1.8-1.2 (48H,

m), 0.8 (6H, t).

825.29 C50H96O8

Not typical TAG structure;

Contain hydrolyzed by-products

with oleic acid diols

F4

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.8-

3.4 (2H, m), 2.4-2.2 (6H,

m), 1.6-1.2 (78H, m), 0.8

(9H, t)

884.6 C53H102O8·H2O TAG-like diols containing

one oleic acid-like diol

F5

5.2 (1H, m), 4.4-4.2 (2, dd),

4.2-4.0 (2H, dd), 3.6 (1.5H,

br), 3.4 (1.1H, m), 2.4-2.2

(6H, m), 1.6-1.2 (77H, m),

0.8 (9H, t)

889.5 C52H100O8·2H2O TAG-like diols containing one

oleic acid-like diol

F6

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.8-

3.4 (3.2H, m), 2.4-2.2 (6H,

m), 1.6-1.2 (64H, m), 1.0

(3H, t), 0.8 (6H, t)

889.7 C55H106O8 TAG-like diols containing

one oleic acid-like or/and one

9-dodecenoic acid-like diols

805.2 C48H92O8·H2O

833.4 C48H92O8·2H2O

F7a

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.8-

3.4 (3.41H, m), 2.4-2.2 (6H,

m), 1.6-1.2 (66H, m), 1.0

(2.6H, t), 0.8 (6H, t)

872.8 C51H98O10 TAG-like diols containing

one 9-dodecenoic acid-like

diol;

TAG-like tetrols containing

one or two oleic acid-like

diols or/and one 9-

dodecenoic acid-like diol

833.4

C47H90O10·H2O;

C45H86O10·2H2O;

C48H92O8·2H2O

805.4 C45H86O10·H2O;

C48H92O8·H2O

F7b

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.8-

3.4 (3.1H, m), 2.4-2.2 (6H,

m), 1.6-1.2 (64H, m), 1.0

(2.7H, t), 0.8 (6H, t)

805.4 C45H86O10·H2O TAG-like diols containing one

9-dodecenoic acid-like diol;

TAG-like tetrols containing one

or two oleic acid-like diols

or/and one 9-dodecenoic acid-

like diol

817.8 C47H90O10

844.8 C49H94O10

F7c

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.8 -

3.4 (3.3H, m), 2.4-2.2

(5.8H, m), 1.6-1.2 (58H,

m), 1.0 (1.3H, t), 0.8 (5.2H,

t)

719.5 C39H74O10·H2O TAG-like diols containing

one 9-decenoic acid- like

diol;


one or two oleic acid-like,

one or two 9-dodenonic acid-

805.6 C45H86O10·H2O

847.6 C48H92O10·H2O

78

like or/and one 9-decenoic

acid- like diols

F8

5.2 (1H, m), 4.4-4.2 (2H,

dd), 4.2-4.0 (2H, dd), 3.6 -

3.2 (6.2H, m), 2.4-2.2

(5.6H, m), 1.6-1.2 (58H,

m), 1.0 (1.0H, t), 0.8 (5.1H,

t)

777.3 C42H80O12 TAG-like hexols containing

one or two oleic acid-like and

one or two 9-dodecenoic

acid-like derived diols;



derivatives and one oleic

acid-like or 9-dodecenoic

acid-like diol;

TAG-like diols containing


diol.

805.3

C44H84O12;

C45H86O10·H2O;

C48H92O8·H2O

877.7 C49H94O12

651.4 C33H62O12

a 1H-NMR Chemical shifts, δ, in CDCl3 (ppm)

b Structures determined based on 1H-NMR and MS (Scheme A2 in the Appendix)

2.3.5.2 HPLC Results

A good separation of PMTAG diols and tetrols was achieved with the HPLC

method. However, standards were not available for all of the polyols hence, HPLC

calibration curves are not available for every component of the polyols in PMTAG Polyol.

Hence the composition of polyols cannot be quantified using the HPLC peaks. However

the HPLC data of PMTAG Polyol and the fractions is helpful for the comparison of

different polyol components in the PMTAG Polyol. The HPLC of PMTAG Polyol is shown

in Figure 2.9 and the HPLC of the fractions of PMTAG Polyol are provided in the

Appendix in Figure. A4.

79

Figure 2.9. HPLC of PMTAG Polyol.

The HPLC showed single peaks for almost all the fractions indicating that a very good

separation was obtained with column chromatography. The HPLC peaks of the PMTAG

polyol fractions were easily assigned to the main structures, i.e., saturated TAGs, diols,

tetrols, and hexols that were detected by 1H-NMR and MS. The analysis of the HPLC of

the PMTAG Polyol based on the succession of the HPLC retention times of its fractions

was carried out seamlessly. The major structures present in the PMTAG polyol were

quantified quite accurately using HPLC relative area with the help of the PMTAG polyol

fractions used as standards.

The HPLC data of the PMTAG Polyol fractions indicate that the saturated TAGs (F1)

eluted first (RT between 2.3 - 2.9 min) and the molecules with the largest number of

hydroxyl groups (F8) eluted last (RT> 31 min). Note that the amount of saturated TAG

structures determined from the relative area of HPLC peak of F1 (~42%) matches closely

the amount of saturated material (~47%) present in the PMTAG starting material. The

saturated TAGs (F1) were followed by the hydrolyzed by-products (F2 and F3) at 7 - 11

Time (min)

10 20 30 40 50 60 70 80

LS

U

0

100

200

300

400

1000

2000

80

min then by the PMTAG diols (F4-F6) at 15.5 to 20.5 min. The mixture of PMTAG diols

of short and long fatty chains eluted between 15 to 21 min. F7, the fraction of PMTAG

comprising PMTAG tetrols with short fatty chains and PMTAG diols with internal and

terminal OH groups eluted at 20.5 to 22.3 min and constituted ~ 15.9 % of the total polyol.

F8 which comprised a mixture of diols, tetrols and hexols eluted last at 30.7-33.1 min.

HPLC area of F8 was ~29% of the total. The area under the HPLC peaks of diols, tetrols

and hexols together constituted ~52% of the total. Note that the relative area of each

fraction singled out from the HPLC of the PMTAG polyol matched very well the value

obtained with the area of the individual HPLC of the fraction to the sum of the areas of the

individual HPLC of the fractions.

Table 2.7. HPLC retention time (RT, min) and relative area (A%) of column

chromatography fraction of PMTAG polyol (F1-F8) obtained from the analysis of the

HPLC of PMTAG Polyol

Fraction RT A%

F1 2.5 - 2.9 43

F2 7.1 - 7.2 1

F3 10.5 - 10.6 1

F4 15.5 - 15.6 5

F5 16.7 - 17.4 2

F6 19.3 - 20.3 1

F7 20.3 - 22.3 15

F8 30.4 - 32.7 30

81

2.3.6 Composition of PMTAG Polyol

The 1H-NMR, MS and HPLC of PMTAG Polyol fractions revealed 42% of

unreacted saturated fatty acids, 8% of PMTAG diols (with two hydroxyl groups), 16% of

a mixture of PMTAG diols and tetrols (with four hydroxyl groups) and 30% of PMTAG

diols, tetrols and hexols (with six hydroxyl groups). The structures detected by 1H-NMR

and MS in the PMTAG polyol fractions (F1-F8) are listed in the Appendix in Scheme A2.

The general structures of PMTAG polyol are shown in Scheme 2.6. These were

determined based on the above data with the help of the structures of PMTAG (see Section

3.2). These include PMTAG diols, PMTAG tetrols and PMTAG hexols, all with terminal

hydroxyl groups (n= 0 in Scheme 2.6) as well as internal hydroxyl groups (n=2 or 8 in

Scheme 2.6). The polyol structures with terminal hydroxyl groups were derived from 9-

decenoic acid (n=0 in Scheme 2.6) and those with internal hydroxyl groups (secondary

hydroxyl groups) were formed from fatty acids like 9-dodecenioc acid (n=2 in Scheme 2.6)

and oleic acid (n=8 in Scheme 2.6).

82

Scheme 2.6. General structures present in PMTAG Polyol (n= 0, 2, 8; m=11 to 20)

2.3.7 Physical Properties of PMTAG Polyol

2.3.7.1 Thermal degradation of PMTAG Polyol

The TGA and DTG curves of PMTAG Polyol are presented in Figure 2.10. The

onset temperature of degradation determined at different early weight loss values ( 1%T ~

215°C, 5%T ~295 °C and 10%T ~320 °C at 1%, 5% and 10%, respectively) were lower by

~ 15 °C than those of PMTAG due to the loss of the terminal hydroxyl groups which occur

before the breakage of the ester bonds. The main DTG peak at 374 °C (arrow 1 in Figure

2.10) is associated with the loss of fatty acid chains resulting from the breakage of the ester

bonds [56, 65]. The small DTG shoulder peak at ~ 450 °C (arrow 2 in Figure 2.10) indicate

a second step of degradation wherein the decomposition of ester groups and others high

83

decomposition temperature fragments and the degradation of the remaining carbonaceous

materials from the previous step were recorded [66].

Figure 2.10: TGA and DTG profiles of PMTAG Polyol.

2.3.7.2 Crystallization and Melting Behavior of PMTAG polyol

The DSC thermograms obtained during cooling and subsequent heating of PMTAG

Polyol are presented in Figure 2.11a and 2.11b, respectively. The corresponding

characteristic temperatures ( onT : onset, offT : offset, and pT : peak temperatures) are listed

in Table 2.8.

The DSC of PMTAG Polyol resemble that of PMTAG in many aspects. The cooling

trace of PMTAG Polyol presented two well-defined exotherms (P1 and P2 in Figure

2.11a). Although not as separated as in PMTAG, P1 and P2 indicate a high and a low

crystallizing portions reminiscent of the stearin- and olein-like portions of PMTAG. The

heating thermogram of PMTAG Polyol displayed also two distinct groups of endothermic

events (G1 and G2 in Figure 2.11b) that are associated with the melting of the stearin- and

olein-like portions of PMTAG Polyol.

Temperature (oC)

100 200 300 400 500

Weig

ht Loss (

%)

0

20

40

60

80

100

DT

G (

%oC

-1)

0.0

0.4

0.8

1.2

1.6

84

Figure 2.11: (a) Crystallization of PMTAG polyol (b) heating profile of PMTAG

polyol.

The crystallization and melting peaks of the stearin-like portion of the polyol occurred

at the positions of those of the PMTAG saturated moieties. For example, P1 of the polyol

(Figure 2.11a) and P1 of PMTAG (Figure 2.4a) presented similar onT (~25.5 °C and~24.5

°C, respectively) and pT (~24 °C and ~23 °C, respectively). This portion of PMTAG Polyol

was constituted primarily of the non-functional TAG structures that were not altered by the

epoxidation and hydroxylation reactions. The low temperature exothermic event P2 of the

olein-like portion of PMTAG Polyol peaked at a relatively higher temperature than the P2

of PMTAG (~14 °C compared to 4 °C, Table 2.8) because of the added OH groups. The

presence of the hydroxyl groups explain also the higher melting peaks of the polyol (in

(a)

-20 -10 0 10 20 30 40

Heat

Flo

w

(Wg

-1)

(E

xo u

p)

0.0

0.2

0.4

0.6

0.8 P1

P2

Temperature (oC)

42.3oC

(b)

Temperature (oC)

-40 -20 0 20 40 60

Heat

Flo

w (

Wg

-1)

(Endo d

ow

n)

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

G2

G1

85

Table 2.8, 3T = 30 °C for PMTAG Polyol and 25 °C for PMTAG). Note that the enthalpy

of crystallization measured for P1 of the polyol was 40 J/g, i.e., 42 % of the total enthalpy

of crystallization of the polyol, reflects the balance between the hydroxyl derivatives and

the saturated components of PMTAG Polyol.

Table 2.8. Thermal data of the PMTAG and PMTAG Polyol obtained on cooling and

heating (5 °C/min). onT , offT , and pT , p= 1-6: onset, offset, and peak temperatures, ,C MH

: Enthalpy, C: crystallization and M: melting.

Temperature (C) Enthalpy (J/g)

Cooling 1T 2T 3T 4T 5T 6T onT offT 1H 2H CH

PMTAG 22.9 4.1 -6.4 -22.7 -31.7 -43.6 24.4 -54.1 24.4 67.8 92.1

Polyol 24.1 13.8 25.5 -4.4 40 54.1 94.1

G2 G1

Heating 1T 2T 3T 4T 5T 6T onT offT MH

PMTAG 45.5 40.1 25.0 13.5 -4 -16.9 -59.3 49.0 24.5 65.6 90.0

Polyol 45.3 40.2 30.4 22.4 1.90 46.7 9.5 86.7 96.2

The crystallization and melting data indicate that PMTAG polyol can be separated into

a saturated-rich solid fraction (P1) and a hydroxyl-rich liquid-like fraction (P2). However,

even if a good separation was obtained, the low melting temperature fraction of PMTAG

Polyol would not remain liquid at room temperature and would solidify in time because of

the close proximity and overlap of its crystallization trace with that of the high melting

temperature fraction. With controlled fractionation protocols, the amount of hydroxyl

groups in each fraction may be controlled to some extent, giving custom-made

86

functionalized materials for use in applications that can range from cosmetics to waxes and

high-end polymers.

2.3.7.3 Flow and Viscosity Behavior of PMTAG polyol

The study of the rheological properties of polyols are very important for the

optimization of their processing and transformation. Selected shear stress versus shear rate

curves recorded for PMTAG Polyol between 40 ºC to 100 ºC are shown in Figure 2.12.

Fits to the Herschel-Bulkley model (Eq. 2.1) are included in the figure (dashed lines in

Figure 2.12). Evident from Fig. 6, share rate – shear stress curves were linear for the whole

shear rates range, except at 40 ºC where it was linear below 650 s-1 only. Application of

Eq. 2.1 to the linear region of the share rate – shear stress data generated power index

values ( n ) all practically equal to unity and no yield stress (straight Lines in Figure 2.12,

R2> 0.99999), indicating a Newtonian behavior. The deviation from the Newtonian

behavior above 650 s-1 at 40 °C is due to the close proximity of this temperature to the

crystallization onset of the material.

Figure 2.12: Shear rate versus shear stress of PMTAG Polyol

Shear Rate (s-1

)

0 200 400 600 800 1000 1200

Sh

ea

r S

tre

ss (

Pa

)

0

50

100

150

200

250

300

90

80

70

C)

(a)

87

Figure 2.13: Viscosity versus temperature measured while cooling PMTAG Polyol

at () 1 °C/min. Dotted lines represent the calculated viscosity using the generalized van

Velzen equation (Eq.2.2). Lower panel represent the residuals in % (RD%) versus

temperature. The cut-off is indicated with a vertical dashed line.

The viscosity versus temperature curve of PMTAG polyol shown in Figure 2.13

presented the typical exponential behavior of liquid hydrocarbons [62, 67]. The fit of the

experimental data to the generalized van Velzen equation (GvVE, Eq. 2.2) was excellent

in the temperature region where PMTAG Polyol was liquid and deviates sharply below 35

°C (cut off line in the lower panel of Figure 2.13). The deviation as represented by the

residuals (RD%) is higher than 1% and increases significantly with decreasing temperature.

The cut-off is consistent with the temperature at which shear stress versus shear rate data

showed a shear thickening limit to the Newtonian behavior of the polyol at high shear rate

(curve obtained at 40 C in Figure 2.12). The sharp increase of RD% (Eq. 2.3) is

understandable because after the cut-off temperature, which is very close to the onset of

Vis

cosity (

Pa.s

)

0.0

0.2

0.4

0.6

0.8

20 30 40 50 60 70 80 90 100 110

RD

%

-4

-2

0

2

4

Temperture (oC)

88

crystallization ( onT ) of the material, liquid-crystal or gel-like states of PMTAG polyol

nucleate and grow very rapidly increasing dramatically the viscosity.

The viscosity of PMTAG polyol was higher than PMTAG at all temperatures due

to the hydroxyl groups which increase the polarity and intermolecular attractive force

between the molecules by hydrogen bonding [68]. The viscosity values of some of the

polyols from highly unsaturated oils that are used for polyurethane applications are; soy

polyol (by ozonolysis): 680 mPa.s at 25 C, canola polyol (by ozonolysis): 500-900 mPa.s

at 25 C, rapeseed oil polyol (epoxidation/hydroxylation): 140 at 40 °C and soy polyol

(epoxidation/hydroxylation): 250-990 at 70 °C respectively[13, 14, 69, 70]. Although the

viscosity PMTAG Polyol at 40 °C (330 mPa.s) doesn’t exactly match these values, it is

close enough and in the range of the feasibility of using the same methodologies to make

polyurethanes without drastic changes to the existing handling and processing techniques.

2.4 Conclusions

1-butene metathesized palm oil (PMTAG) is revealed to be different from the natural

oil in terms of composition, chemical structure and physical properties. The metathesis

reaction preserved the saturation level of ~50% of the natural oil and yielded 24.9 mol%

of fatty acids with terminal double bonds. The DSC thermal analysis revealed that

PMTAG, although with a significantly different composition, was constituted of a high-

melting and a low-melting portions akin to the well-known stearin and olein fractions of

palm oil. It is therefore possible to fractionate PMTAG using standard methods to obtain

feedstock with desired unsaturation levels. Furthermore, its flow behavior and viscosity

profile, which is similar to common highly unsaturated vegetable TAG oils, makes it

89

suitable to be processed and transformed into more valuable materials by existing

technology.

Fully functionalized polyols were successfully produced from PMTAG by standard

epoxidation and hydroxylation. The PMTAG polyol with a relatively high hydroxyl value

(155 mg KOH/g) and primary diols, tetrols and hexols and internal hydroxyl groups which

match the PMTAG double bond configuration map, is a suitable starter for a variety of

applications not possible with a non-transformed TAG oil, including rigid and flexible

polyurethane foams. Also inherited from PMTAG, PMTAG Polyol presented a high

melting and low melting molecular fractions that can be directly related to the stearin-like

and olein-like fractions of PMTAG. With adequate melting temperature and viscosity

profile, also in the range of those of polyols made from unsaturated vegetable oil, PMTAG

polyol would lend itself to easy processing and transformation. The cross-metathesis

reaction transformed the natural palm oil into a more useful material with structural and

physical characteristics that improved its prospects as a substrate for further transformation

and the manufacture of a variety of materials including waxes, cosmetics and

polyurethanes.

Acknowledgements We would like to thank the Grain Farmers of Ontario,

Elevance Renewable Sciences, Trent University, the GPA-EDC, Ontario Ministry of

Agriculture, Food and Rural Affairs, Industry Canada and NSERC for financial support.

90

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96

3 Water-Blown Bio-Based Rigid and Flexible Polyurethane

Foams from 1-Butene Metathesized Palm oil Polyol1

3.1 Introduction

Polyurethanes (PUs) are macromolecules containing urethane linkages (-NH-CO-O-

) that are either formed based on the reaction of isocyanate groups and hydroxyl groups

[1], or via non-isocyanate pathways, such as the reaction of cyclic carbonates with amines

[2], self-polycondensation of hydroxyl-acyl azides or melt transurethane methods [3].

Judicious selection of reactants enables the production of a wide range of polyurethane

products such as polyurethane elastomers [4], sheets [4], adhesives [5], coatings [6], and

foams [7] etc.

PU foams are light weight, have good insulation properties, excellent strength to

weight ratio, and impressive sound absorbing properties [1]. Furthermore, their physical

properties can be tailored to a large extent by varying the structure and composition of the

reacting monomers, amount of catalyst and other additives like glycerin, water etc., as well

as the reaction conditions used in the foam formulation [8]. In the case of water blown

polyurethane foams, the reaction of water and isocyanate produces carbon dioxide gas

1 A version of this Chapter is filed as a US provisional patent: U.S. Provisional Patent Application

#61971475, (filed August, 2013), “Metathesized Triacylglycerol Palm Polyols for Use in Polyurethane

Applications and Their Related Physical Properties,” S.S. Narine, Prasanth. K. S. Pillai, S.Li, L.Bouzidi

and A.Mahdevari and Submitted for a publication in Industrial Crops and Products.

97

which forms into small air bubbles. The diffusion of further carbon dioxide inflates the air

bubbles leading to a well-defined cell structure [9]. PU foams are classified as rigid or

flexible according to compressive strength value, and other parameters such cross link

density and hydroxyl value (OH value) of the starting polyol [1]. The market for PU foams

is very large and growing due to high demand across a wide range of industries such as

automotive, building and construction, and packaging [10, 11]. The worth of the global

polyurethane foams market was $46.8 billion in 2014 and is estimated to reach $72.2 billion

by 2020 [12].

Traditionally, PU foams are prepared by the reaction of diisocyanates or

polyisocyanates with petroleum-derived polyols [1]. The development of polyurethanes

from renewable and environmentally friendly feedstock has become the subject of

increasing research because of sustainability and other environmental concerns [13].

Vegetable oils are a particularly promising alternative feedstock for the synthesis of polyols

and polyurethanes because they are biodegradable, available in large quantities, and are

relatively low-cost [14]. A significant body of literature reporting on the synthesis of

polyols and polyurethanes from natural oils is readily available (see for example PU foams

from soybean oil [15, 16], safflower oil, corn oil, sunflower seed oil, linseed oil [17],

rapeseed oil [18], and cotton seed oil [19]).

Palm oil is one of the cheapest and most produced oils in the world that is touted as

a viable renewable feedstock for the economical industrial production of polyols and

polyurethanes [20-23]. However, palm oil does not lend itself easily to chemical

modification because of its relatively high level of saturation (50% fatty acids) which caps

the levels at which it can be functionalized and hence the hydroxyl value of its polyols as

98

compared to highly unsaturated TAG oils such as soybean oil [24]. Furthermore, similar to

most other natural oils, its double bonds are internal and dispersed in the 95%

triacylglycerols (TAGs) and 5% diacylglycerols (DAGs) composing the oil [24-26] which

result in polyols with secondary hydroxyl groups and dangling chains. Such polyols are

less reactive towards polymerization, and known to lead to incomplete crosslinking and

imperfections in the polymer network [7, 27]. The regions where dangling chains are

present do not support stress when the sample is loaded, and act as plasticizers that reduce

the rigidity of the polymer [27, 28]. In fact, the hydroxyl value and the position of the

hydroxyl groups in the fatty chain, the molecular weight of the polyol and the presence of

dangling chains, are the most important factors which affect the properties of polyurethanes

[27-29].

Current research efforts revolve around finding the transformation routes that would

increase the potential of the natural oils as viable sources for polyols and PU foam products.

Such efforts include improving existing synthesis routes, developing new chemistries and

optimizing processing conditions. Olefin metathesis is an example of such novel

approaches that our research group is using as a platform for improved and more suitable

feedstock for the formulation of bio-based materials, particularly polyols and PUs. The

foams of the present work were formulated with a polyol obtained from a product of the

cross-metathesis of 1-butene and palm oil (PMTAG) (so-called PMTAG Polyol). The

chemical and physical properties of the modified TAG material (PMTAG) and its polyol

have already been reported [30].

99

Scheme 3.1. Cross linked polyurethane foam from MDI and PMTAG Polyols. Hexol is

used as a model polyol structure.

PMTAG Polyol is a relatively low molecular weight material comprising ~52% of

functional hexols, tetrols and diols, with half of the hydroxyl groups in terminal positions

[30]. The structures of the polyol with terminal hydroxyl groups were derived from 9-

decenoic acid and those with internal hydroxyl groups (secondary hydroxyl groups) were

100

formed from fatty acids like 9-dodecenioc acid and oleic acid[30]. The unique structure

and composition of PMTAG Polyol and related thermal and rheological properties

indicated enhanced reactivity and kinetics that bode well for further transformation of the

material at manageable reaction conditions into starters and materials for various polymer

applications such as polyurethane foams. The polymerization of PMTAG Polyol into PU

foams as exemplified by a model hexol structure is shown in Scheme 3.1.

The present contribution reports on the preparation and characterization of rigid and

flexible foams from PMTAG Polyol. The effect of terminal hydroxyl PMTAG Polyols on

the physical properties of the polyurethane foams is particularly highlighted. Rigid foams

with densities ranging from 93 kgm-3 to 250 kgm-3, and flexible foams with densities

ranging from 106 kgm-3 to 193 kgm-3 were prepared and characterized by FTIR to confirm

the urethane linkage. The morphology of the foams was examined with scanning electron

microscopy (SEM). Their thermal decomposition and thermal transition behaviours were

determined by thermogravimetric analysis (TGA) and differential scanning calorimetry

(DSC), respectively. The compressive strength of the rigid and the flexible foams were

determined with a texture analyzer.


3.2.1 Materials

PMTAG Polyol [30] was synthesized in our laboratory from PMTAG, a butene

cross-metathesized palm oil product provided by Elevance Renewable Sciences (ERS,

Bolingbrook, Il). Dibutin Dilaurate (DBTDL) and glycerin (99.5 %) were purchased from

Sigma-Aldrich, Canada, and perchloride acid (70%) from Fisher Scientific, Canada. N, N-

101

Dimethylethanolamine (DMEA) from Fischer chemical (USA), diphenylmethane

diisocynate (MDI) from Baer Materials Science (Pittsburgh, PA), and polyether-modified

surfactant (TEGOSTAB B-8404) from Goldschmidt Chemical Canada.

3.2.2 Polymerization Method

The amount of each component of the polymerization mixture was based on 100 parts

by weight of total polyol. All the ingredients, except MDI, were weighed into a beaker and

then MDI was added to the beaker using a syringe. The ingredients were then mechanically

mixed vigorously for 8 to 20 s and then poured into a cylindrical Teflon mold (60 mm

diameter and 35 mm long), which was previously greased with silicone release agent. The

mold was sealed with a hand tightened clamp. The sample was cured for four (4) days at

45 C and post cured for one (1) day at room temperature. Rigid and flexible foams of

different densities were prepared using the same polymerization protocol and formulation

recipe. During the polymerization step, the amounts of mixture was controlled to achieve

the desired densities.

3.2.3 Chemistry and Physical characterization techniques

3.2.3.1 Fourier Transform Infrared Spectroscopy (FTIR)

FTIR spectra were obtained with a Thermo Scientific Nicolet 380 FT-IR

spectrometer (Thermo Electron Scientific Instruments, LLC, USA) equipped with a PIKE

MIRacleTM attenuated total reflectance (ATR) system (PIKE Technologies, Madison, WI,

USA.). Solid samples were loaded onto the ATR crystal area, and sample spectra were

acquired over a scanning range of 400-4000 cm-1 for 32 repeated scans at a spectral

resolution of 4 cm-1.

102


The thermogravimetric analysis (TGA) was carried out on a TGA Q500 (TA

Instruments, DE, USA) equipped with a TGA heat exchanger (P/N 953160.901).

Approximately 8.0 – 15.0 mg of sample was loaded onto the open TGA platinum pan. The

sample was heated from 25 to 600 °C under dry nitrogen at a constant rate of 10 °C/min.


The thermal transition behavior of the PMTAG Polyol foams was investigated

using a Q200 model (TA Instruments, New Castle, DE) by modulated DSC following

ASTM E1356-03 standard. The sample (3.0 – 6.0 mg) in hermetically sealed aluminum

DSC pan was first equilibrated at 25 °C and heated to 150 °C at 10 °C/min (first heating

cycle). The sample was held at that temperature for 10 min and then cooled down to -90

°C at 10 °C/min, and subsequently reheated to 150 °C at the same rate (second heating

cycle). Modulation amplitude and period were ±1 °C and 60 s, respectively.

The “TA Universal Analysis” software was used to analyze the TGA and DSC

thermograms. The characteristics of non-resolved peaks were obtained using the first and

second derivatives of the differential thermogravimetry (DTG) and differential heat flow.

3.2.3.4 Texture Analysis - Compressive Strength

The compressive strength of the foams were measured at room temperature using

a texture analyser (TA-TX HD, Texture Technologies Corp, NJ, USA). Samples were

prepared in cylindrical Teflon molds of 60-mm diameter and 36-mm long. The cross head

speed was 3.54 mm/min with a load cell of 750 Kgf. The load was applied until the foam

was compressed to approximately 15% and 65% of the original thickness of the rigid and

103

flexible foams, respectively. The compressive strength of the rigid and flexible foams were

calculated at "10% deformation" method according to the standard (literature used as

reference). The flexible foams were compressed to the maximum extent (65%) of its

original thickness. In the case of Rigid Foams, the compressive strength is the stress

prevailing at 10% strain [31] Also compressive strength at 6% deformation of rigid foam

and 25% for flexible foams are reported for comparison purpose.

3.2.3.5 Scanning Electron Microscopy (SEM)

A scanning electron microscope (SEM, model Tescan Vega II), was used under

standard operating conditions (10 keV beam) to examine the pore structure of the foams.

Each sample (~2 cm × 2 cm and 0.5 cm thick), cut from the centre of foam samples

prepared in cylindrical Teflon molds of 60-mm diameter and 36-mm long, was coated with

a thin layer of carbon (~30 nm thick) to ensure electrical conductivity in the SEM chamber

and prevent the buildup of electrons on its surface. All images were acquired using a

secondary electron detector to show the surface features of the samples.

3.2.4 Preparation of PU rigid and flexible foams

Rigid and flexible polyurethane foams were prepared from PMTAG polyol and MDI

using a previously published method [7]. The formulation recipes used to prepare the rigid

and flexible foams are presented in Table 3.1. The amount of each component was based

on 100 parts by weight of total polyol. The characteristics of the PMTAG Polyol (OH value

and acid value) and of the diphenylmethane diisocyanate (MDI) are provided in Table 3.2.

The amount of MDI which was used for the polymerization of both the rigid and flexible

foams was determined in order to achieve an isocyanate index of 1.2 (NCO to OH ratio of

1.2 to 1).

104

The rigid foams were prepared based on a total hydroxyl value of 450 mg KOH/g. In

this case, glycerine (16 parts), a poly hydroxyl cross linker, was added into the reaction

mixture in order to obtain the targeted hydroxyl value (see Table 3.1). DBTDL and DMEA

are the two catalysts that were used for the foam preparation. DBTDL is a cross linking

catalyst which favours the gelling reaction, and DMEA, the co-catalyst, functions as a

blowing catalyst during the polymerization process [1, 32]. The catalyst ratios were fixed

to 1 part of the total weight of the polymerization mixture in the formulation of the rigid

foams. The choice of DBTDL and DMEA and fixed ratio was based on the fairly good

compressive strength previously obtained for rigid PUR foams prepared from terminal

hydroxyl polyols [7].

The flexible foams were prepared based on a total hydroxyl value of 155 mg KOH/g.

In this case, the catalyst amount was fixed to 0.1 parts in order to produce the most flexible

foams with least compressive strength [33]. Note that no glycerine was added in the flexible

foam formulation.

Table 3.1. Formulation Recipe for Rigid and Flexible PMTAG Polyol Foam

Ingredients Parts by weight

Rigid Foam Flexible Foam

PMTAG polyol 100 100

OH: NCO ratio 1:1.2 1:1.2

Glycerol 16 0

Water 2 2

Surfactant 2 2

Catalyst 1 0.1

Co-catalyst 1 0.1

105

Table 3.2. Composition and properties of PMTAG Polyol and diphenylmethane

diisocyanate (MDI)

PMTAG Polyola MDIb

Description: Light yellow waxy solid Description: Dark brown liquid

Composition:

Diols, tetrols and hexols: 52%

Terminal hydroxyl polyol: 24%

Internal hydroxyl polyol: 28%

Composition:

Polymeric MDI: 40-50%

(4, 4’ Diphenylmethane Diisocyanate): 30-40%

MDI mixed isomers: 15-25%

Melting Point (°C) 48 Boiling Point (°C) 208

OH Value (mg KOH/g) 155 NCO (wt%) 31.5

Acid value (mg KOH/g) 2 Functionality 2.4

Equivalent weight (g/mol) 362 Equivalent weight (g/mol) 133

Viscosity @ 40°C (mPa.s) 329-335 Viscosity @ 25 °C (mPa·s) 200

Bulk density (Kgm-3) 1234

a[30]

b[Bayer Materials Science (Pittsburgh, PA)]

Table 3.3. Reactivity profile for the processing of PMTAG Polyol rigid and flexible foams

Cream time (s) Gel time (s) Rise time (s)

Rigid Foam 8 - 12 24 - 28 72 - 74

Flexible Foam 12 - 15 29 - 31 75 - 80

As can be seen in Table 3.3 listing the cream time, gel time and rise time, the rigid

foams formed relatively faster than the flexible foams. The difference in reactivity was

attributed to the extra catalyst and co-catalyst (additional 1 part of both) and the addition

of highly reactive glycerol in the rigid foam formulation (see Table 3.1). Higher catalyst

concentration enabled shorter mix times and the further reactivity profiles of foaming

processes. The addition of glycerol in the polymerization mixture for the rigid foam

106

formulation drives the crosslinking reaction by speeding the entire polymerization reaction

compared to flexible foam formulations [33].

As shown in Figure 3.1a and 3.1b displaying representative pictures of PMTAG

Polyol rigid Foam and PMTAG Polyol flexible Foam, respectively, the foams were white

to very light yellow with a smooth surface. The flexible foams felt softer to the touch

compared to the rigid foams. The color and smooth texture were preserved for all the foams

regardless of density.

(a) (b)

Figure 3.1: Pictures of (a) Rigid PMTAG Polyol Foam, and (b) Flexible PMTAG Polyol

Foam

3.3 Results and discussion

3.3.1 FTIR Characterization of Foams

The FTIR spectra of PMTAG Polyol rigid and flexible foams are shown in Figure

3.2. The formation of urethane linkages was evidenced by the characteristic broad

absorption band of NH groups and of C=O of the urethane linkage at 3300-3400 cm-1 and

at 1700 cm-1, respectively [22].The band centered at 1519 cm-1 characteristic of C-N bonds

also confirmed the formation of urethane bonds in the foams [34]. However, as shown by

107

the weak band at 2278 cm-1, some NCO groups were still present. This indicated that the

isocyanate was not fully reacted [22, 28]. The overlapping peaks between 1710 and 1735

cm-1 suggested the presence of urea and isocyanurates in the PMTAG Polyol foams. The

peak at 1417 cm-1 reveals the presence of small amount of isocyanurate trimers, indicating

the occurrence of the trimerization reaction of diisocyanates during the foaming process.

The stretching bands of the ester groups are particularly visible at 1744 cm-1 (C=O), 1150-

1160 cm-1 (O-C-C) and 1108-1110 cm-1 (C-C(=O)-O). The stretching vibration of -C-H in

-CH3 and -CH2 groups in the aliphatic chains were also visible at 2923 cm-1, and 2853 cm-

1 respectively [35].

Figure 3.2. Typical FTIR spectra of the PMTAG Polyol foams. (1) PMTAG Polyol Rigid

Foam and (2) PMTAG Polyol Flexible Foam

3.3.2 SEM analysis of PMTAG Polyol Foams

Figure 3.3a and 3.3b show SEM images of the rigid and flexible PMTAG Polyol

foams, respectively. Average cell size of rigid and flexible PMTAG polyol foams were 270

Wave Number (cm-1

)

500100015002000250030003500

Absorb

ance

0.00

0.05

0.10

0.15

0.20

0.25

(1)

(2)

1519 c

m-1

1417 c

m-1

2278 c

m-1

2853 c

m-1

2923 c

m-1

3333 c

m-1

108

± 40 µm and 386 ± 55 µm, respectively. The cell density from the SEM micrographs was

~21 cells per mm2 for the rigid PMTAG polyol foams and ~18 cells per mm2 and flexible

PMTAG polyol foams.

It was apparent from the SEM picture that the cells in the rigid PMTAG polyol foam

were closed and uniformly arranged. The cells in the flexible foams were also closed but

displayed non-uniform size (cell size ranges from 250 µm to 500 µm) and distribution. The

highly compact and closed cell structure of the rigid PMTAG Polyol foams is due to their

high cross linking density attributed to the presence of more primary hydroxyl groups by

the addition of glycerin [36], while the absence of glycerin cross linker and the different

rate of crosslinking of terminal versus internal hydroxyls present in the PMTAG polyol

during flexible foam formulation resulted in less uniform cells [36]. Rigid and flexible

foams with closed cell walls are suitable for thermal insulation applications [37].

(a)

(b)

Figure 3.3. Typical SEM micrographs of (a) Rigid PMTAG Polyol foams and (b) Flexible

PMTAG Polyol Foam

109

3.3.3 Thermal Stability of Foams

Figure 3.4a and 3.4b show the TGA/DTG profiles of rigid and flexible PMTAG

polyol foams, respectively. The onset temperature of degradation of the rigid foam (RF)

was consistently lower than that of the flexible foam (FF), whether determined at 1, 5 or

10% weight loss ( 1%T = 180 ºC and 216 ºC for RF and FF, respectively, 5%T = 253 ºC and

272 ºC for RF and FF, respectively, and 10%T = 275 ºC and 292 ºC for RF and FF,

respectively). This may be due to the degradation of the short chain urethane structure from

the low molecular weight glycerin cross linker. The DTG curves of both rigid and flexible

Polyol foams showed four prominent peaks ( DiT , i=1-4, in Figure 3.4a and 3.4b) which

indicate a multi stage decomposition process. The first peak centered at 1DT = 296-300 °C,

which involved a total weight loss of ~12 to 17 %, is related to the dissociation of urethane

bonds, taken place either through the dissociation into isocyanate and alcohol, or the

formation of primary or secondary amines, olefin and carbon dioxide [38, 39].

Figure 3.4: TGA and DTG profiles of (a) PMTAG rigid foam and (b) PMTAG flexible

foam.

(a)

100 200 300 400 500

0

20

40

60

80

100

DT

G

/%

/oC

Weig

ht

Lost

(%

)

296 o

C

Temperature (oC)

360 o

C 434 o

C

470 o

C

(b)

100 200 300 400 500

20

40

60

80

100

DT

GA

/

%/o

C

Weig

ht

Lost

(%

)

Temperature (oC)

30

3 o

C

360 o

C

434 o

C

470 o

C

110

The second and third DTG peaks (360 and 430 °C) are associated with the

decomposition of the soft segment (polyol back bone) into carbon monoxide, carbon

dioxide, carbonyls (aldehyde, acid, acrolein) olefins and alkenes [39, 40]. These

decomposition steps involved the largest weight loss with ~45-50 % of the total. The last

DTG peak ( 4DT at ~ 470 °C) is related to the decomposition of fragments such as esters or

more strongly bonded fragments associated with the polyol backbone that occur at high

temperature, and probably to the degradation of remaining carbonaceous materials from

the previous step [41].

The rates of the urethane degradation were almost the same (maximum of ~0.40 %/

°C) for the rigid and flexible PMTAG Polyol foams. Also the rates of each step of thermal

degradation were similar for the rigid and flexible foams except in the last step at ~470 °C

where the rigid and flexible PMTAG Polyol foams displayed rates of 0.54 %/°C and

0.27%/°C, respectively. This may be due to the degradation of the left over fragments from

the glycerol backbone used for the preparation of the rigid foams. The overall thermal

stability of the PMTAG Polyol based foams is good and compares fairly well with the

commercial foams and other vegetable based polyol foams [23, 33]..

3.3.4 DSC of Rigid and Flexible Foams

DSC analysis was carried out to study the thermal phase transitions of the PU foams.

Figure 3.5a and 5b show the DSC profiles obtained during the second heating cycle of the

rigid and flexible PMTAG polyol foams, respectively. Three inflection points due to glass

transitions ( g lowT (RF: -10.2 °C, FF: -21.5 °C), intgT (~34 °C), g highT (~50 °C) in Figure

3.5a and 3.5b) were observed in the baseline of the thermograms of both rigid and flexible

111

PMTAG Polyol foams. No melting peaks were observed for any of the foams, indicating

their high cross linking density. The g lowT of the rigid PMTAG Polyol foam was higher

than that of the flexible PMTAG Polyol foam, probably because of higher crosslink density

[29]. Recall that OH value was enhanced to 450 mg KOH/g by the addition of glycerine in

the rigid foam formulation. Both rigid and flexible foam displayed almost same intgT at

~34 °C and g highT at ~50 °C.

The jump in heat capacity (ΔCp) was ~0.4 Jg-1K-1 at g lowT , 0.1 Jg-1K-1 at intgT , and

0.12-0.22 Jg-1K-1 at g highT , suggesting that a large number of molecular chains were

associated with the relaxation of the molecular motion of the polyol backbone [20]. The

magnitude of molecular relaxation of the urethane segment ( g highT at ~50 °C) was much

smaller compared to g lowT due to the intramolecular and intermolecular crosslinking,

which restricts the molecular motion of the hard segment of urethane [20].

Figure 3.5. Typical DSC curves of (a) Rigid PMTAG Polyol Foam and (b) Flexible

PMTAG Polyol Foam.

(a)

-50 0 50 100

0.16

0.20

0.24

0.28Density-164 kgm

-3

Temperature (oC)

Heat

Flo

w

(W

g-1

)

Tg low

Tg int

Tg high

Temperature (oC)

(b)

-50 0 50 100

-0.16

-0.12

-0.08

-0.04

0.00

0.04Density-160 kgm

-3

Heat

Flo

w

(W

g-1

)

Tg low

Tg int

Tg high

112

3.3.5 Compressive Strength of PMTAG Polyol Foams

The mechanical properties of the foams were studied by the compressive stress-strain

measurements. Figure 3.6a and 3.6b represent the compressive strength versus strain of

the rigid and flexible PMTAG Polyol foams, respectively. A linear segment indicative of

the elastic region of the rigid and flexible foams was observed at ~2-4% (Figure 3.6a) and

~8-10% (Figure 3.6b), respectively. The elastic region was followed by a long plateau in

which the stress varied moderately. The plateau region in Figure 3.6a and 3.6b resulted

from the buckling of the cell walls upon further compression of the foams [35]. The curve

related to rigid foam of density 250 kg/m3 (Figure 3.6a) displayed an elastic region only

up to 2% strain with a maximum compressive strength at 5% deformation. Further

compression of the rigid foam of density 250 kg/m3 above 5% caused the breakage of the

resultant foam (Figure 3.6a). This indicate that the cross-linking density and brittleness of

the rigid foams may have increased with the increase in density [29].

The elastic region in the flexible foams observable at ~8-10% (Figure 3.6b) was

followed by a long plateau up to ~25% strain in which the stress varied moderately and

which indicates the buckling of the cells, and then by a relatively steep increase indicative

of the collapse of the cells. Note that the elastic region as well as the plateau were more

extended in the flexible foam than in their rigid foam counterparts, suggesting a very

different structure of the walls. Each region is determined by some mechanism of

deformation. The cell morphology such as cell size, cell wall thickness etc. has a critical

role in the compressive strength of the foams [28]. The extent of bending of the cell walls

during the compression process indicates the compressive strength of the foam such that

the thickness of the cell wall, shape and size of the cells, type of cells (open or closed) etc.,

113

have significant impact on the compressive strength [42]. Linear elasticity is controlled by

cell wall bending and, in case of closed cells, by stretching of the cell walls. The plateau is

associated with the collapse of the cells. When opposing cell walls touch, the further strain

compresses the solid itself increasing stress rapidly, and giving the final so-called

densification region [35].

Figure 3.6. (a) Compressive strength versus strain curves of PMTAG Polyol foams (a)

rigid foam (b) flexible foams.

Figure 3.7a and 3.7b shows the density versus compressive strength of the rigid and

flexible PMTAG polyol foams at different strain %. As seen in Figure 3.7a and 3.7b, the

compressive strength of both rigid and flexible foams increased with increasing foam

density. The highest compressive strength value for the rigid foam (2.5 MPa, Figure 3.7a)

and for the flexible foam (1.07 MPa, Figure 3.7b) was obtained for the foams with the

highest density, i.e., 250 kg/m3 and 193 kg/m3 respectively. The increase in density of the

material increases the number of additional cross links and hence the compressive strength

of the material [42].

0 2 4 6 8 10 12 14

Co

mp

ers

siv

e S

tre

ngth

(

MP

a)

0.0

0.4

0.8

1.2

2.02.42.8

161

109

146

100

Density (kg/m3)

250

Strain (%)

(a) (b)

Strain (%)

0 5 10 15 20 25 30

Com

pre

ssiv

e S

trength

(

MP

a)

0.0

0.5

1.0

1.5

2.0

106

126

146

164

193

Density (kg/m3)

114

Figure 3.7. Density (kg/m3) versus compressive strength (MPa) of PMTAG Polyol foams

at 6% and 10% deformations (a) rigid foam (b) flexible foam.

The compressive strength value of the rigid foams obtained from PMTAG Polyol are

higher than those prepared from natural TAG oil polyols such as palm oil polyol [42],

soybean oil polyol [7] and canola oil polyol [7]. Table 3.4 shows the compressive strength

values of rigid foams obtained from palm oil [43], soybean oil [7] and canola oil polyol

[7]. As can be seen in Table 3.4, the rigid foams prepared with polyols from palm oil and

soybean oil presented compressive strengths which were half that of the rigid PMTAG

polyol foam, understandably because the PMTAG polyol has less dangling chains and a

relatively large amount of primary hydroxyl groups compared to the natural oils which

possessed internal hydroxyl groups only. Even the rigid foam prepared from the canola oil

polyol, which was free of dangling chains, presented a lower compressive strength at 10%

deformation than the rigid PMTAG polyol foam of similar density. This may be due to the

presence of highly reactive tetrols and hexols in the PMTAG polyol, which considerably

amplified the cross linking density of the PMTAG polyol foams compared to canola oil

polyol.

Density (kgm-3

)

100 150 200 250

Co

mp

ressiv

e s

tre

ngth

(M

Pa

)

0.5

1.0

1.5

2.0

2.5

3.0

6%

10%

(a)

Density (kgm-3

)

80 100 120 140 160 180

Co

mp

ressiv

e s

tre

ngth

(M

Pa

)

0.0

0.4

0.8

1.2

1.6

2.0

10%

25%

(b)

115

Table 3.4. Compressive strength of vegetable polyol based rigid foams from the

literature[7, 43].

Rigid Foam from Density

(kg/m3)

Compressive

Strength (MPa)

Polyol Specification

OH value

(mg KOH/g)

dangling

chains

Terminal

OH-groups

Palm Oil Polyol 200-300 1.00-1.50 300 Yes No

Soybean Oil Polyol 160 0.32 185 Yes No

Canola oil polyol 160 0.77 152 No Yes (triols)

3.3.6 Recovery of Flexible Foams

Figure 3.8a shows the percentage of recovery in thickness of flexible PMTAG

Polyol foams as a function of time. The recovery in thickness of the flexible foams were

measured after its maximum compression (65%) using a Vernier caliper. The recovery in

thickness was recorded every minute for the first ten minutes, then after 1, 2, 24 and 48 h.

In all the flexible foams, more than 60% recovery was obtained in less than 2 min, and ~

70 - 80 % after 5 min. At any given time, the flexible foams with highest density achieved

the highest recovery, with a maximum of 91% for the flexible foam having the largest

density (193 kgm-3). The recovery after 48 h of the flexible foams, increased linearly with

density (Figure 3.8b) ( 2R = 0.9710), with a slope of 0.5 % recovery per kgm-3.

The flexibility of the foam was linked to the crosslinking density of the material. The

compression of the low density flexible PMTAG polyol foams may rupture some of the

cells due poor cell wall thickness. This prevents the easy and full recovery of the low

density flexible foams. The increase in density of the flexible foam increases the number

116

of cross links and hence the cell wall thickness which allows the cells to withstand the

stress without breakage.

Figure 3.8. (a) Recovery of PMTAG Flexible Foam as a function of time (min); (b)

Recovery of PMTAG Flexible Foam after 48 h as a function of density.

Vegetable oil based polyols with only internal hydroxyl groups are widely used for

flexible foam applications [44]. This is due to the less tightened cross link network formed

by the internal OH polyols facilitated by the presence of dangling chains. However, the

present data show that flexible foams with good recovery can be achieved from the

PMTAG polyol even if it possesses terminal hydroxyl groups. The complex structure of

PMTAG polyol allows their use in the preparation of functional rigid foams as well as high

performing flexible foams. PMTAG polyol may also be partially substituted with

commercial petroleum based polyols for the preparation of flexible foams with good

physical properties similar to what was achieved with soybean oil polyol [15] and palm oil

polyol [23].

(a)

0 3 6 9 12 1000 2000 3000

Re

co

ve

ry

(%

)

20

40

60

80

100

106

129

146

172

193

Density (kg/m3)

Time (min)

(b)

60 90 120 150 180 210

Recovery

(%

)

50

60

70

80

90

100

Density (kgm-3

)

117

3.4 Conclusions

1-butene cross metathesized pal oil polyol (PMTAG Polyol), a mixture of diols,

tetrols and hexols with 24.1 mol% terminal hydroxyl groups was found to be an ideal

material for the preparation of polyurethane foams. Water blown rigid (densities ranging

from 93 kgm-3 to 250 kgm-3) and flexible (densities ranging from 106 kgm-3 to 193 kgm-3)

foams were successfully prepared from PMTAG polyol and fully characterized with FTIR,

SEM, TGA and DSC. The cellular structure of the foams as evaluated from SEM comprised

of small sized (rigid and flexible foams cell size: 270±40µm and 386±55 µm, respectively)

and closed cells. Both the rigid and flexible PMTAG foams presented better thermal

degradation stability compared to the commercially available vegetable-based and

petroleum-based polyurethane foams. The rigid and flexible PMTAG Polyol foams

displayed a multi-step glass transition attributable to the molecular motion of the polyol

backbone at ~ -10 °C and ~ -20 °C and molecular motion of the urethane segments at higher

temperatures (~ 34 °C and ~50 °C for the rigid and flexible, respectively. The rigid PMTAG

polyol resulted in foams with higher compressive strengths compared to the highly

unsaturated vegetable oil (soybean oil, canola oil) polyol derived rigid foams because of

its terminal hydroxyls. The flexible foams produced from the PMTAG Polyol displayed

good compressive strength with 90% recovery in thickness after compression.

The good thermal stability and the closed cell structure suggests the suitability of the

rigid and flexible foams for thermal insulation applications. The structural and physical

properties of the foams of the present study substantiates the possibility of PMTAG polyol

to compete favorably with the commercial bio-based as well as petroleum standard polyols

for making polyurethane foams at an industrial scale.

118

Acknowledgements We would like to thank the Grain Farmers of Ontario, Elevance

Renewable Sciences, Trent University, the GPA-EDC, Ontario Ministry of Agriculture,

Food and Rural Affairs, Industry Canada and NSERC for financial support.

3.5 References

[1] Szycher M. Szycher's handbook of polyurethanes: CRC press, 1999.



2011;50(11):6517-27.

[3] More AS, Gadenne B, Alfos C, Cramail H. AB type polyaddition route to thermoplastic

polyurethanes from fatty acid derivatives. Polymer Chemistry. 2012;3(6):1594-605.

[4] Kong X, Narine SS. Physical properties of polyurethane plastic sheets produced from

polyols from canola oil. Biomacromolecules. 2007;8(7):2203-9.



2003;23(4):269-75.






Society. 2007;84(1):65-72.

[8] John J, Bhattacharya M, Turner RB. Characterization of polyurethane foams from

soybean oil. Journal of Applied Polymer Science. 2002;86(12):3097-107.

[9] Doyle EN. The development and use of polyurethane products: McGraw-Hill New

York, NY, 1971.

[10] Babb DA. Polyurethanes from Renewable Resources. In: Rieger B, Kunkel A, Coates

GW, Reichardt R, Dinjus E, Zevaco TA, editors. Synthetic Biodegradable Polymers2012.

p. 315-60.

[11] David J, Vojtová L, Bednařík K, Kučerík J, Vávrová M, Jančář J. Development of

novel environmental friendly polyurethane foams. Environmental Chemistry Letters.

2010;8(4):381-5.

119

[12] Firm MRCaC. Polyurethane Foam Market by Type (Flexible Foam, Rigid Foam), by

End-User Industry (Bedding & Furniture, Building & Construction, Electronics,

Automotive, Footwear, Packaging, Others), by Geography - Global Trends & Forecasts to

2020.marketsandmarkets.2015

(http://www.marketsandmarkets.com/PressReleases/polyurethane-foams.asp.).



Reviews. 2012;52(1):38-79.

[14] Petrović ZS. Polyurethanes from vegetable oils. Polymer Reviews. 2008;48(1):109-

55.






linseed oil and polyol esters. J Am Oil Chem Soc. 1972;49(11):615-8.



2002;84(3):591-7.









23.





interesterification. Journal of the American Oil Chemists Society. 2002;79(11):1137-44.




120

[26] Ong AS, Goh S. Palm oil: a healthful and cost-effective dietary component. Food &






2007;84(2):173-9.



2002;10(1):49-52.

[30] Prasanth S.Pillai SL, Laziz Bouzidi and Suresh S. Narine. 1-Butene Metathesized

Palm Oil & Its Polyol derivatives: Structure, Chemical composition and Physical

Properties. Submitted to Industrial Crops and Products. 2015.

[31] Tate PM, Talal S. Compressive properties of rigid polyurethane foams. Polymers &

Polymer Composites. 1999;7(2):117-24.

[32] Ashida K. Polyurethane and related foams: chemistry and technology: CRC press,

2006.





[35] Gu R, Konar S, Sain M. Preparation and characterization of sustainable polyurethane

foams from soybean oils. Journal of the American Oil Chemists' Society.

2012;89(11):2103-11.



[37] Prociak A, Pielichowski J, Sterzyñski T. Thermal diffusivity of polyurethane foams

measured by the modified ångström method. Polymer Engineering & Science.

1999;39(9):1689-95.

[38] Javni I, Petrović ZS, Guo A, Fuller R. Thermal stability of polyurethanes based on

vegetable oils. Journal of Applied Polymer Science. 2000;77(8):1723-34.

[39] Shufen L, Zhi J, Kaijun Y, Shuqin Y, Chow W. Studies on the thermal behavior of

polyurethanes. Polymer-Plastics Technology and Engineering. 2006;45(1):95-108.

121


vegetable and animal fats. Bioresource Technology. 2003;87(1):35-9.


Journal of Thermal Analysis and Calorimetry. 2009;95(3):977-83.

[42] Thirumal M, Khastgir D, Singha NK, Manjunath B, Naik Y. Effect of foam density

on the properties of water blown rigid polyurethane foam. Journal of Applied Polymer

Science. 2008;108(3):1810-7.

[43] Chian K, Gan L. Development of a rigid polyurethane foam from palm oil. Journal of

Applied Polymer Science. 1998;68(3):509-15.

[44] Banik I, Sain M. Water blown soy polyol-based polyurethane foams of different

rigidities. Journal of Reinforced Plastics and Composites. 2007.

122

4 Fractionation Strategies for Improving Functional

Properties of Polyols and derived Polyurethane Foams from

1-butene Metathesized Palm Oil2

4.1 Introduction

Palm oil is one of the most abundant and inexpensive renewable commodity oils in

the world, making it an economical alternative feedstock for the polymer industry [1].

However, its saturation level (~50% saturated fatty acids) limits the hydroxyl value of

polyols derived from the native oil [2]. Furthermore, because of the internal position of its

double bonds, native palm oil produces polyols with dangling chains at the unsaturated

sites which after polymerization leads to incomplete crosslinking and imperfections in the

polymer network [3, 4]. Several strategies have been employed to address these handicaps,

including the recent cross metathesis of palm oil with 1-butene [5].

Olefin cross metathesis enables the shortening of unsaturated fatty acids at the

location of the double bonds, producing low molecular weight TAG products with terminal

double bonds: structures that can yield polyols with primary hydroxyls on functionalization

2 A version of this chapter is filed as a US provisional patent: U.S. Provisional Patent Application

#62107935, (filed January, 2015), “Polyols from the Fractions of Metathesized Triacylglycerols and

Polyurethanes from such Polyols and Their Physical Properties,” S.S. Narine, Prasanth. K. S. Pillai, S.Li,

L.Bouzidi and A.Mahadevari and Submitted for a publication in Industrial Crops and Products

123

[5-7]. Such terminal hydroxyl polyols are free of pendant chains arising from the

unsaturated fatty acid moieties, with reduced steric hindrances and dangling chains in

subsequent polyurethane networks [8]. However, since metathesis does not affect the

saturated moieties of the natural oil, the saturated fatty acid moieties of the native oil (~50

%) still limit the hydroxyl number and provides steric hindrances and dangling chains in

resulting polyurethanes.

The starting material of the present work derives from 1-butene cross metathesis of

palm oil (PMTAG), stripped of short chain olefins, which has been previously well

characterized [5]. PMTAG comprises approximately 25% terminal double bonds, 28%

shortened unsaturated fatty acids, and ~47% of saturates inherited from the natural oil.

PMTAG was easily converted into polyols by standard epoxidation and hydroxylation [5]

which were then used to make improved rigid and flexible polyurethane foams [8].

However, although the compressive strength of the foams was significantly enhanced due

to the reduction of dangling chains associated with the terminal unsaturated fatty acids,

undesirable long pendent chains were still present due to the relatively large number of

saturates left from the natural oil. Opportunely, PMTAG is comprised of two relatively

separate portions akin to the stearic and oleic portions of the natural palm oil, indicating

that it can be separated into high and low melting fractions. If a facile fractionation is

possible, the low melting portion should contain less of the highly saturated components

and therefore should make a feedstock which would help mitigate the problems associated

with the plasticizing action of the dangling chains in rigid foams. The material should also

be more easily processed because of a lower melting temperature and should present less

124

steric hindrance during functionalization to produce polyol and also in crosslinking process

to form polyurethanes.

Crystallization is one of the most effective and economical means for fractionating

vegetable oils [9]. Crystallization fractionation consists of two steps, first the cooling of

the liquid oil using specific processing conditions to a crystallization temperature and then

removal of the solid fat from the liquid oil [10]. During the cooling process, the high

melting components of the oil crystallize first and these can be removed from the liquid oil

via filtration or sedimentation. The parameters of an effective fractionation by

crystallization are determined by the cooling rate, the crystallization temperature and the

crystallization time [11]. Fractionation can be entirely from the melt (dry) or can be solvent

mediated. Solvent aided crystallization, although more expensive, is more efficient and

allows for facile filtration since the viscosity of the liquid oil is reduced when a solvent is

present [11]. Furthermore, it can be advantageous if the solvent was a part of the further

transformation of the material, such as in the synthesis of polyols. For this reason both

solvent and dry crystallization methods were used to fractionate PMTAG in an attempt to

optimize yield and composition of the fractions, particularly with respect to the synthesis

of polyols and rigid polyurethane foams.

Several studies regarding the fractionation of palm oil by dry as well as solvent aided

crystallization have been published [12-14]. The present work reports on the fractionation

of PMTAG and the synthesis of polyols from the fractions. The fractionation was

performed by dry as well as solvent mediated crystallization for optimum yield and quality

of the liquid fraction. Quality here refers to maximum unsaturation content. The polyols

were synthesized by standard epoxidation and hydroxylation reactions, and characterized

125

chemically and physically to determine their suitability as monomers for the preparation of

polyurethane foams. The rigid and flexible foams were prepared with similar densities

(~160 kg m-3) to allow for comparison. The urethane linkage of the foams was confirmed

by FTIR. Their morphology, thermal decomposition and thermal transition behaviours

were studied by scanning electron microscopy (SEM), thermogravimetric analysis (TGA)

and differential scanning calorimetry (DSC), respectively. The compressive strength of the

foams were determined with a texture analyzer.


4.2.1 Materials

PMTAG was provided by Elevance Renewable Sciences (ERS, Bolingbrook, II).

Dichloromethane (DCM), ethanol (anhydrous), toluene, potassium hydroxide, and sodium

thiosulfate were purchased from ACP Chemical Int. (Montreal, Quebec, Canada) and used

without further treatment. Formic acid (88 wt %) and hydrogen peroxide (30 wt% in H2O),

iodine monochloride (95%), potassium iodide (99%), dibutin dilaurate (DBTDL), glycerin

(99.5 %) and phenolphthalein were purchased from Sigma-Aldrich Canada Co. (Oakville,

Ontario, Canada). Perchloric acid (70%), N, N-dimethylethanolamine (DMEA) was

purchased from Fisher Scientific, USA, diphenylmethane diisocynate (MDI) from Bayer

Materials Science (Pittsburgh, PA), and polyether-modified surfactant (TEGOSTAB B-

8404) from Goldschmidt Chemical Canada. HPLC grade solvents were obtained from

VWR International, Mississauga, ON.

126

4.3 Chemistry Characterization Techniques

4.3.1 Titrimetric Methods (OH value, Acid value, Iodine value)

Iodine and acid values of SF- and LF- PMTAG were determined according to ASTM

D5554-95 and ASTM D4662-03, respectively. OH and acid values of the polyols were

determined according to ASTM S957-86 and ASTM D4662-03, respectively.

4.3.2 Proton Nuclear Magnetic Resonance Spectroscopy (1HNMR)

1H-NMR spectra were recorded CDCl3 on a Varian Unity-INOVA at 499.695 MHz

using an 8.6 μs pulse with 4 transients collected in 16 202 points. Datasets were zero-filled

to 64 000 points and a line broadening of 0.4 Hz was applied prior to Fourier transforming

the sets. 1H chemical shifts are internally referenced to CDCl3 (7.26 ppm). The spectra

were processed using spinwork NMR Processor, version 3.

4.3.3 Fourier Transform Infrared Spectroscopy (FTIR)

FTIR spectra of the foams were obtained using a Thermo Scientific Nicolet 380 FT-

IR spectrometer (Thermo Electron Scientific Instruments, LLC, USA) equipped with a

PIKE MIRacleTM attenuated total reflectance (ATR) system (PIKE Technologies,

Madison, WI, USA.). Foam samples were loaded onto the ATR crystal area and held in

place by a pressure arm. The spectra were acquired over a scanning range of 400-4000 cm-

1 for 32 repeated scans at a spectral resolution of 4 cm-1.

4.4 Physical Characterization Techniques

4.4.1 Thermogravimetric Analysis (TGA)

The TGA measurements were carried out on a Q500 model (TA Instruments, DE,

USA) under dry nitrogen of 40 mL/min for balance purge flow and 60 mL/min for sample

127

purge flow. Approximately 8.0 – 15.0 mg of sample was loaded into the open TGA

platinum pan then heated from 25 °C to 600 °C at a constant rate of 10 °C/min.

4.4.2 Differential Scanning Calorimetry (DSC)

DSC was performed on a Q200 model (TA Instruments, New Castle, DE) under a

nitrogen flow of 50 mL/min. Samples between 3.5 and 6.5 (± 0.1) mg were run in

hermetically sealed aluminum DSC pans. DSC measurements of the PMTAG fractions and

PMTAG Polyols were run in standard mode. The sample was equilibrated at 90 °C for 10

min to erase thermal memory, and then cooled at 5.0 °C/min to -90 °C where it was held

isothermally for 5 min, and subsequently reheated at 5.0 °C/min to 90 °C. PMTAG was

also cooled at 0.1 C/min and 1 C/min to investigate the effect of cooling rate on its

crystallization behavior.

In order to obtain a better resolution of the glass transition, the foams were

investigated using modulated DSC following the ASTM E1356-03 standard. The sample

was first equilibrated at 25 °C and heated to 150 °C at 10 °C/min (first heating cycle), held

at that temperature for 5 min and then cooled down to -90 °C at 10 °C/min, and

subsequently reheated to 150 °C at the same rate (second heating cycle). Modulation

amplitude and period were 1 °C and 60 s, respectively.

The “TA Universal Analysis” software version 5.4 was used to analyze the DSC

thermograms and extract the peak characteristics. Characteristics of non-resolved peaks

were obtained using the first and second derivatives of the differential heat flow.

128

4.4.3 Rheology

A temperature-controlled Rheometer (AR2000ex, TA Instruments, DE, USA) fitted

with a 40 mm 2° steel geometry was used to measure the viscosity and flow property of the

PMTAG fractions and PMTAG Polyols. Temperature control was achieved by a Peltier

attachment with an accuracy of 0.2°C. Shear Stress was measured at each temperature by

varying the shear rate from 1 to 1200 s-1. Measurements were taken at 10 °C intervals from

high temperature (100 °C) to 10 °C below the DSC onset of crystallization temperature of

each sample. The viscosity versus temperature data were collected at 200 s-1 using the

constant temperature rate method (1.0 °C/min). Data points were collected from each

sample’s melting point up to 110 °C at intervals of 1 °C. The viscosity obtained in this

manner was in very good agreement with the measured viscosity using the shear rate/share

stress.




0

nK Eq. 4.1

Where denotes the shear stress, 0 is the yield stress below which there is no

flow, K the consistency index and n the power index. n depends on constitutive

properties of the material. For Newtonian fluids n = 1, shear thickening fluids, 1n and

for shear thinning fluids, 1n .

129

4.4.4 Scanning Electron Microscopy (SEM)

A scanning electron microscope (SEM), model Tescan Vega II, was used under

standard operating conditions (10 keV beam) to examine the pore structure of the foams.

A sample of approximately 2 cm x 2 cm and 0.5 cm thick was cut from the centre of a 60-

mm diameter and 36-mm long specimen. The sample was coated with a thin layer of carbon

(~30 nm thick) using an Emitech K950X turbo evaporator to ensure electrical conductivity

in the SEM chamber and prevent the buildup of electrons on the surface of the sample. All

images were acquired using a secondary electron detector to show the surface features of

the sample.

4.4.5 Compressive Strength

The compressive strength of the foams was measured at room temperature using a

texture analyzer (Texture Technologies Corp, NJ, USA). Samples were prepared in

cylindrical Teflon molds of 60-mm diameter and 36-mm long. The cross head speed was

3.54 mm/min with a load cell of 750 kgf. The load was applied until the foam was

compressed to approximately 15% of the original thickness for the rigid foam, and 65%

for the flexible foam.

4.5 Fractionation of PMTAG by dry and solvent mediated crystallization

The fractionation protocol for PMTAG was informed by its cooling thermal

transition behavior. Figure 4.1 shows the DSC cooling thermograms of PMTAG obtained

with 0.1 °C/min, 1.0 °C/min and 5.0 °C/min. The corresponding thermal data (onset ( OnT

), offset ( OffT ) and peak ( pT ) temperatures) are listed in the Appendix in Table A2.

130

Figure 4.1. Crystallization thermograms of PMTAG obtained at 0.1 °C/min, 1

°C/min and 5 °C/min.

As can be seen, all the thermograms of Figure 4.1 present three distinguishable peaks

(P1, P2 and P3 in Figure. 4.1) indicative of three different crystallization events

representing a high and two low temperature crystallizing portions [15]. The lowest

temperature peak (P3) was well separated in the 0.1 C/min experiment only. Although P3

is related to a specific well-defined molecular portion of PMTAG (the lowest crystalizing

portion), it cannot be easily separated from the main low temperature fraction expressed

by P2. In fact, the DSC trace reveals the presence of a high and a low temperature

crystallizing portions reminiscent of the stearin and olein of the natural palm oil [5, 16].

The combined P2 and P3 are the recording of the olein-like portion of PMTAG and P1 the

recording of its stearin-like portion. The data from Figure 4.1 motivates a cooling protocol

and crystallization temperature ranges that would be optimal for the separation of PMTAG

(a)

Temperature (oC)

-20 -10 0 10 20 30 40

Heat

Flo

w (

Wg

-1)

(

Exo u

p)

0.00

0.01

0.02

0.03

0.25

0.50

0.75

1.0

0.1

5.0

P1

P2

P3

Rate

(oC

/min

)

131

into a high and low melting fractions. As is indicated by the DSC thermograms, a better

separation would be obtained with the slowest cooling of PMTAG. One then can choose

an isothermal crystallization temperature (CT ) where only the nucleation of the high

crystallizing molecules (stearin-like portion) are occurred, i.e., above at least the offset of

the first peak to avoid the formation of the low melting crystals (olein-like portion). The

isothermal crystallization time period (Ct ) should be chosen to allow for the stearin-like

portion to solidify. The choice of CT and

Ct will dictate the yield and quality of the

separation provided a proper filtration of the solids from the liquid can be achieved. The

same considerations are valid for both the dry and solvent crystallization, taking into

account their actual crystallization parameters and more importantly, the boiling point of

the solvent, in our case 39.6 °C for DCM.

Four (04) dry fractionation experiments (method labeled D), and one (01) solvent

mediated crystallization experiment (method labeled S) were used to optimize the

fractionation of PMTAG with a compromise between “quality” and yield of the liquid

fraction. The details of the fractionation experiments are presented in Table 4.1.

4.5.1 Dry crystallization experiments

Four sets of fractionation experiments were conducted with the dry crystallization

method (F1-F4 in Table 4.1). Between 200 and 260 g of melted PMTAG was equilibrated

at 90 °C in a round bottom flask placed in a temperature controlled water bath (Julabo

FP50-ME, Julabo USA Inc., Vista, CA). The sample was cooled down at a prescribed rate

(0.05 or 0.035 °C/min) to CT at which point it was crystallized isothermally under vigorous

132

stirring (500 rpm) during Ct . The solid fraction was filtered from the liquid with filter paper

(Fisherbrand™, P5) and with the help of a vacuum pump (BUCHI V-700, Switzerland).

4.5.2 Solvent Mediated Crystallization Experiment

For the solvent mediated fractionation (F5 in Table 4.1), 5 kg of melted PMTAG

was mixed under gentle stirring with 5 kg (3.8L) of DCM (PMTAG to DCM ratio of 1:1

(wt/wt)) in a preheated (37 °C) 20-L jacketed reactor (Heb Biotechnology Co., Ltd, Xi’an,

China). The reactor was kept at 37 °C with a connected temperature controlled circulator

(Hack Phoenix II P1 Circulator, Thermo Electron, Karlsruhe, Germany) until the

dissolution was complete. The PMTAG was then brought under stirring to a temperature

of 2 °C at which the stirring was turned off and the mixture was left to crystallize

isothermally for 24 h allowing for the stearin-like portion of PMTAG to crystallize and

eventually sediment. The crystallized material was then filtered from the liquid easily and

very effectively with filter paper (Fisherbrand™, P8, 15 cm) and vacuum (300 Torr).

Table 4.1. Fractionation data of PMTAG. aCT : Crystallization temperature; b

Ct :

isothermal crystallization time

Experiment Mass (g) Cooling Rate (°C/min) aCT (°C) b

Ct (h) LF: Yield

(wt %)

F1 200 0.050 35.0 7.0 28

F2 250 0.035 39.5 9.0 45

F3 244 0.035 35.0 6.5 37

F4 258 0.035 29.0 11.0 22

F5 5000 Quiescent 2.0 24.0 70

133

4.6 Synthesis of the Polyols

Polyols were synthesized from LF- and SF-PMTAG in a two-step reaction;

epoxidation by formic acid and hydrogen peroxide (H2O2), followed by hydroxylation

using water and perchloric acid (HClO4) as the catalyst following a previously reported

method, [5]. The chemical route is described in Scheme 4.1

Scheme 4.1. Synthesis route of polyols from the liquid and solid fraction of PMTAG

(n=0, 2, 8; m=11 to 20).

This is a well-established economical route to produce polyols with maximum

hydroxyls. In this method the double bonds are converted into oxirane moieties and the

epoxy groups are converted into hydroxyl groups by ring opening reaction with suitable

reagents like HClO4 and H2O to give the polyol. The polyols produced from liquid and

solid fractions are labeled LF-Polyol, and SF-Polyol, respectively.

134

4.6.1 Epoxidation

Formic acid (88%; 200g) was added to a solution of fractionated PMTAG (200 g) in

DCM (240 mL). The mixture was cooled to 0 °C in an ice bath, and hydrogen peroxide (30

%, 280 g) was added drop wise while stirring with a mechanical stirrer (500 to 600 rpm).

After the addition of hydrogen peroxide, the mixture was raised to 50 °C and kept at this

temperature with stirring until the reaction was complete. The reaction was monitored by

a combination of TLC and 1H-NMR, and was deemed complete after 48 h. The reaction

mixture was then diluted with 250 mL of DCM, washed with water (200 mL × 2), and then

with saturated sodium hydrogen carbonate (200 mL × 2), and again with water (200 mL ×

2). The resulting epoxide was rotary evaporated to remove the solvent, and then was dried

over anhydrous sodium sulphate.

4.6.2 Hydroxylation

Approximately 200 g of crude fractionated PMTAG epoxide was dissolved at room

temperature in a 500 mL mixture of THF/H2O (3:2) containing 14.5 g of perchloric acid.

The resultant mixture was stirred at room temperature for 36 h, a time after which the

reaction which was monitored by a combination of TLC and 1H-NMR was deemed

complete. The reaction mixture was poured into 240 mL water and extracted with CH2Cl2

(2×240 mL). The organic phase was washed with water (2 × 240 mL), followed by 5%

aqueous NaHCO3 (2 × 200 mL), and then with water again (2 × 240 mL), and then dried

over Na2SO4. After removing the drying agent by filtration, the solvent was removed with

a rotary evaporator and further dried by vacuum overnight, giving a light yellow grease-

like solid.

135

4.7 Polymerization Method

The formulation recipes for the preparation of rigid and flexible polyurethane foams

from LF-Polyol are provided in Table 4.2. The ingredient amounts are based on 100 parts

by weight of polyol. The amount of MDI was calculated based on an isocyanate index 1.2

(NCO to OH ratio of 1.2 to 1). All the ingredients, except MDI, were weighed into a beaker,

and pre-weighed MDI was added to the beaker using a syringe. The resulting mixture was

mechanically mixed vigorously for 10 to 20 s. the mixture was immediately transferred

into a cylindrical Teflon mold (60 mm diameter and 35 mm long) previously greased with

a silicone release agent, and then sealed with a hand tightened clamp. The sample was

cured for four (4) days at 40 C and post cured for one (1) day at room temperature.

Table 4.2. Formulation Recipes for Rigid and Flexible Foams

Parts by weight

Ingredient Rigid Foams Flexible Foams

LF-Polyol 100 100


Glycerin 14.5 0

Water 2 2

Surfactant 2 2

Catalyst 1 0.1

Co-catalyst 1 0.1

136


4.8.1 Results of the fractionation of PMTAG

DSC investigation of the fractions confirmed that the fractionation was generally

effective and that a wide range of compositions for the liquid and the solid fractions can be

obtained by tuning the experimental parameters. The DSC cooling and heating

thermograms obtained in experiment F2 representative of the liquid and solid fractions of

PMTAG are presented in Figures 4.2a and 4.2b, respectively. The DSC thermograms of

the liquid and solid fractions obtained by the different fractionation methods are provided

in the Appendix in Figures. A5 – A6 and the corresponding thermal characteristics in

Table A3.

Figure 4.2. Typical DSC thermograms of the liquid (LF) and solid fractions (SF) of

PMTAG. (a) cooling and (b) heating (both at 5 C/min)

(a)

Temperature (oC)

-30 -15 0 15 30 45

Heat

Flo

w

(W

g-1

)

(E

xo u

p)

LF

SF

(b)

Temperature (oC)

-30 -15 0 15 30 45 60 75

Heat

Flo

w

(W

g-1

)

(E

xo u

p)

LF

SF

137

As can be seen in Figure 4.2a, the cooling thermograms of the solid fractions

displayed both the high and low temperature exotherms, indicating that it retained a part of

the olein-like portion of PMTAG. The DSC data of the LF- and SF-PMTAG are provided

in the Appendix Table A4. The enthalpy of the exotherm relevant to the olein-like part of

the solid fraction varied depending on the experiment but its onset of crystallization

remained constant and equal to what was measured for the starting PMTAG (see Figure

4.1). This indicates that the liquid was not selectively trapped in the solid.

F1, F2 and F5 experiments yielded liquid fractions comprising some of the stearin

portions of the PMTAG. However, as evident from the leading peak of LF in Figure 4.2a,

the onset of crystallization (~14 C) as well as the enthalpy were much lower than those of

PMTAG, indicating that the highest crystallizing temperature compounds of the stearin

portion were effectively removed. F3 and F4 experiments yielded liquid fractions

comprising the olein portion of PMTAG only but with relatively low yields (~37 %wt/wt

and 22 %wt/wt, respectively, Table 4.1). The onset temperature of crystallization of the

liquid fractions shifted to sub ambient temperatures, and their heating thermograms were

missing the highest melting peaks at ~ 47 C (Figure 4.2b). This indicates that the stearin

portion of the liquid fraction was depleted from the highest crystallizing components of

PMTAG and enriched with the unsaturated and the short saturated moieties.

The acid value of the SF- and LF- PMTAG fractions were all lower than 0.8 mg

KOH/g, indicating a very low free fatty acid content. The iodine value (IV) of the solid

fractions ranged from ~35 to ~36, much less than the 52 IV value of PMTAG, indicating

the extent at which the fraction was depleted from the unsaturated elements of PMTAG.

138

The liquid fractions of the PMTAG presented an IV of ~60 to ~61, higher than PMTAG,

which confirms that enrichment of the liquid fractions with olein-like molecules.

F2 which provided the liquid fraction with the best compromise between the

decrease in onset temperature of crystallization (13.5 C) and yield (45 %wt/wt) and which

presented the highest iodine value and lowest acidity value was selected for further analysis

and use for the synthesis of polyols. The selected fractions simply labelled LF-PMTAG

and SF-PMTAG for the liquid and solid fractions of PMTAG, respectively. The

corresponding polyols are also simply labeled LF-Polyol and SF-Polyol, respectively.

4.8.2 1H-NMR Characterization of the PMTAG fractions

1H-NMR spectra and corresponding 1H-NMR chemical shifts of LF- and SF-

PMTAG are provided in the Appendix in Figure A7-A8 and Table A5, respectively. As

expected, LF- and SF- PMTAG displayed the same chemical shifts observed for PMTAG

[5]. Scheme 4.2 represents the possible structures of LF- and SF-PMTAG as revealed by

1H-NMR.

The fatty acid profiles calculated based on the relative area under the characteristic

1H-NMR peaks are presented in Table 4.3. the terminal double bond, internal double bond

and saturated fatty acid contents were calculated based on the integrated protons under the

5.0 - 4.8 ppm, δ 5.5-5.3 ppm and 1.0-0.8 ppm peaks, respectively. Note that based on their

very low acid value (<1 mg KOH/g), the analysis of the 1H-NMR of LF and SF-PMTAG

was performed assuming that only TAG structures were present.

139

Scheme 4.2. Possible TAG structures in LF-and SF-PMTAG. n=0, 2, 8; m= 11 to

20.

Table 4.3. Fatty acid profile of SF-PMTAG and LF-PMTAG calculated based on the

relative area under the characteristic 1H-NMR peaks assuming TAG structures only. The

PMTAG data are provided for comparison purposes. TDB: Terminal double bonds; IDB:

Internal double bonds; FA: Fatty acid; SFA: Saturated fatty acid

FA with TDB (mol%) FA with IDB (mol%) SFA (mol%)

n=0 in Scheme 4.1 n=3 in

Scheme

4.1

n=8 in

scheme

4.1

Total

LF-PMTAG 21.1 14.1 16.7 30.8 48.1

SF-PMTAG 20.7 13.2 13.5 26.7 53.2

PMTAG 24.9 15.8 12.6 28.4 46.7

LF-PMTAG comprised more structures with internal double bonds (~31 mol%) and

structures with terminal double bonds (~21 mol%) than SF-PMTAG (~26 mol% and ~20

mol%, respectively). LF-PMTAG also comprised less saturated fatty acid chains than SF-

PMATG (~48 mol% compared to ~53 mol%, Table 4.3). The relatively large decrease in

140

the onset temperature of crystallization and offset temperature of melting of LF-PMTAG

is attributable also to a relatively higher number of TAGs with short saturated moieties

including trisaturated TAGs of the starting material such as trimyristoylglycerol (MMM)

and 1,2-dimyristoyl-3-palmitoyl-sn-glycerol (MMP).

4.8.3 Characterization of the polyols synthesized from LF- and SF-PMTAG

The polyols obtained from the liquid and solid fractions (LF-Polyol and SF-Polyol,

respectively) presented OH values of 184 and 136 mg KOH/g, respectively. Their acid

value was less than 4 mg KOH/g. These chemical characteristics are very suitable for the

further transformation of the polyols into polyurethane foams. The OH value of LF-Polyol

is understandably much higher than the OH value measured for the polyol obtained from

the non-fractionated PMTAG.

The structure of the LF-Polyol and SF-Polyol was determined based on the analysis

of 1H-NMR characteristic chemical shifts. The 1H-NMR data are provided in the Appendix

in Figures A9-A10 and Table A6. The 1H-NMR presented the peak characteristic of the –

OH groups (δ 3.8-3.4 ppm) but not the peak of the epoxides (δ 2.8-2.4 ppm) indicating that

the conversion to hydroxyl groups was complete. The polyols exhibited the chemical shifts

of methylene at δ 5.27 ppm and 4.2-4.0 ppm, and methine protons at δ 4.4-4.2 ppm typical

of TAG glycerol backbones. Furthermore, the peaks the methine protons presented a ratio

of 1:1 indicative of the integrity of the TAG backbone, confirming that the hydrolysis of

the TAG was avoided. Internal and terminal hydroxyls (diols, tetrols and hexols) were

detected in both LF-and SF-Polyols. The amount of hydroxyls as estimated by 1H-NMR

was ~47 %mol in SF-Polyol and~52 %mol in LF-Polyol. The percentage of terminal

hydroxyls in both LF- and SF-Polyols was ~21%. There were more non-terminal hydroxyls

141

in LF-Polyol than in unfractionated PMTAG Polyol (so called PMTAG Polyol) or SF-

Polyol. The possible structures of the polyols are shown in Scheme 4.3.

Scheme 4.3. Possible structures of LF- and SF-Polyols (n= 0, 2, 8; m=11 to 20)

4.8.3.1 Thermal Decomposition of LF- and SF-Polyols

The DTG profiles of LF-and SF-Polyols are shown in Figure 4.3. The corresponding

data are provided in the Appendix in Table A7. The DTG data indicate that the polyols

synthesized from the fractions undergo degradation mechanisms similar to the polyols

made from PMTAG [5]. The DTG curves presented a weak and broad peak centered at ~

220 °C followed by a large peak at 375 - 400 °C and a small shoulder at ~ 450 °C ( 1DT ,

2DT , and 3DT , respectively, in Figures. 4.3) indicating three steps of degradation. The first

step which involved ~1 to 3% weight loss may be due to the loss of hydroxyl groups [17].

The second DTG peak, where ~ 50 - 67% weight loss was recorded, is associated with the

breakage of the ester bonds [18]. Note that this mechanism of degradation was also

dominant in the starting LF- and SF-PMTAG. The small DTG shoulder at ~ 450 °C ( 3DT

142

in Figure. 4.3) indicate the decomposition high temperature fragments and of remaining

carbonaceous materials from the previous steps [17].

Figure 4.3. DTG of LF- and SF-Polyols

4.8.4 Crystallization and Melting Behavior of LF- and SF- Polyols

The crystallization and heating profiles (both at 5 °C/min) of LF- and SF-Polyols

are shown in Figures 4.4a and 4.4b, respectively. The corresponding thermal data are

provided in the Appendix listed in Table A8. As can be seen in Figure 4.4a, the three

peaks in the cooling thermograms of LF- and SF-Polyols (P1, P2 and P3 in Figure 4.4a),

although poorly separated, mirror the peaks observed in the thermograms of LF- and SF-

PMTAG indicating that the two-portion distribution of the starting fractions was preserved

in the polyols. Such a DSC trace indicates that although possible, one cannot separate easily

the high and low melting portions of the polyols. One can also note that the lowest

temperature peak (P3 in Figure 4.4a) is much more prominent in the polyols compared to

their starting material indicating a particular effect of the OH groups on the transition

behavior of the different collections of polyol molecules.

Temperature (oC)

100 200 300 400 500

DT

G

(%

oC

-1)

LF

SF

TD3

TD2

TD1

143

The cooling and heating thermograms of the polyol synthesized with the solid

fractions of PMTAG shows significant differences with those of the liquid Fraction. SF-

Polyol crystallized at 5 C higher temperature than LF-Polyol and presented extra peaks at

the high temperature side of the thermogram (P1 and P1’ of SF at the right side of P1 of

LF in Figure 4.4a). The endotherms of its melting trace were visibly separated contrary to

the greatly overlapped endotherms of LF-Polyol. The crystallization traces of the polyols

are directly related to their unbalanced olein-like/ stearin-like composition, wherein, SF-

Polyol comprised the saturated TAGs (P1 in Figure 4.4a), partially functionalized TAGs

with long saturated moieties (P1’ in Figure 4.4a) as well as higher level hydroxyls such as

tetrols and hexols.

The melting behavior of the polyols is directly related to the degree of separation

in crystallization temperature of “families” of molecules present. The melting peaks of SF-

Polyol are well separated contrary to those of LF-Polyol because of large difference

between the stearin-like molecules (as represented by P1 in Figure 4.4a) and the

functionalized molecules from the olein-like molecules of SF-PMTAG. The occurrence of

a prominent exotherm during the heating of SF-Polyol is an indication of a crystallization

mediated by melt that resulted in the shifting of its offset temperature to ~50 °C closer to

~45°C of LF-Polyol which did not experience a detectable exotherm. This relatively

intense transformation was probably experienced by a substantial number of partially

functionalized TAGs in SF-Polyol. The melting point of LF-Polyols as determined by its

offset temperature of melting was ~45 ºC, a value close to that of PMTAG Polyol: 47 ºC

[5]. This indicates that similar reaction temperatures and equipment can be used for the

further transformation of LF-Polyol into polyurethane foams.

144

Figure 4.4. DSC thermograms of LF- and SF-Polyols obtained from the liquid

fractions and solid fractions of PMTAG during (a) Cooling (5.0 C/min), and (b)

subsequent heating (5 °C/min).

4.8.5 Flow Behavior and Viscosity of LF- and SF-PMTAG Polyols

Selected shear stress versus shear rate curves recorded for LF- Polyol between 30 ºC

to 100 ºC are shown in Figure 4.5 a. Fits to the Herschel-Bulkley model are included in

the figure (dashed lines in Figure. 4.5a). Evident from Figure 4.5a, share rate – shear stress

curves of the LF Polyol were linear for the whole shear rates range, except at 40 ºC where

it was linear below 500 s-1 only, indicating Newtonian behavior. Similar curves indicating

a Newtonian flow within 50 ºC to 90 ºC were obtained for SF-Polyols (data not shown).

The data collected below the onset of crystallization of LF-Polyol (~29 °C) and SF-Polyol

(~32 °C) indicated that the sample has crystallized. Figure 4.5b presents the viscosity

versus temperature plot obtained during cooling at 1 °C/min for LF- and SF-Polyols. As

(a)

Temperature (oC)

-10 0 10 20 30 40

Heat

Flo

w

(Wg

-1)

(

exo u

p)

P2P3

P1

P2

P3

P1

LF

SF

(b)

Temperature (oC)

0 15 30 45 60

Heat

Flo

w

(W

g-1

)

(end

o d

ow

n)

SF

LF

G1 G2

145

evident from the figure, the viscosity of LF-Polyol was higher at all temperatures with the

difference decreasing with increasing temperature. Although relative molecular size could

have played a role, this difference is mainly attributable to a higher number of hydroxyls

in LF-Polyol, as manifest in the OH value. Note that the viscosity of LF-Polyol is also

higher than that of PMTAG Polyol [5, 19], also attributable to the higher OH value of LF-

Polyol compared to PMTAG Polyol [20].

Figure 4.5. (a) Shear rate- shear stress of LF-Polyol), (b) viscosity versus

temperature of LF- and SF-Polyols. Solid lines in (a) are fits to the Herschel-Bulkley model

(Eq. 4.1).

4.9 Polyurethane Rigid and Flexible Foams

Because of its high OH value, favorable thermal transition properties, particularly its

advantageous melting behavior, and suitable viscosity profile, LF-polyol was selected for

making rigid and flexible polyurethane foams. The same density was targeted for the

foams. Rigid foam of density 163 kgm-3 and flexible foam of density 161 kgm-3 were

prepared from LF-Polyol (see formulation recipe in Table 4.2) by the same protocol that

was used for the preparation of PMTAG Polyol foams [8].

(a)

Shear Rate (s-1

)

0 200 400 600 800 1000 1200

Sh

ea

r S

tre

ss

(Pa

)

0

100

200

300

400

500

50

T (oC)

60

70

80

90

40

o C

(b)

Temperature (oC)

45 65 85

Vis

cosity

(P

a.s

)

0.0

0.1

0.2

0.3

0.4

0.5

SF

LF

146

4.9.1 FTIR of LF-PMTAG Polyol Foams

Figure 4.6 represents the FTIR spectra of the rigid and flexible foams prepared

from LF-Polyol. One can first notice that there is no significant difference between the two

spectra. The broad absorption bands of NH groups centered at 3300-3400 cm-1 and C=O at

1700 cm-1 confirms the presence of urethane linkages [21]. The band centered at 1510-

1520 cm-1 is characteristic of C-N bonds in the urethane linkage [22]. The band at 2270

cm-1 related to NCO groups indicates that the isocyanates was not fully reacted [21, 23].

The overlapping peaks between 1710 and 1735 cm-1 suggest the presence of urea and

isocyanurates in the foams. The peak at 1410-1420 cm-1 reveals the presence of

isocyanurate trimers, indicating the occurrence trimerization reaction of diisocyanates

during the foaming process. The characteristic band related to ester carbonyl (C=O) of the

polyol backbone is visible at 1744 cm-1. The stretching vibration of -C-H in -CH3 and -CH2

groups in the aliphatic chains is visible at 2915-2925 cm-1 and 2850-2860 cm-1, respectively

[24].

147

Figure 4.6. Typical FTIR spectra of the rigid (RF) and flexible foams (FF) prepared from

LF-Polyol.

4.9.2 SEM Analysis of LF-Polyol Foams

Figures 4.7a and 4.7b shows SEM images of the rigid and flexible foams,

respectively. one can notice that the rigid foam displayed more compact and uniform closed

cells compared to flexible foam because of the effect of the terminal hydroxyl glycerin

cross linker added in the rigid and not in the flexible foam formulation [25]. In the absence

of a glycerin cross linker, the terminal and internal hydroxyl groups in the same polyol

which cross links at different rates during the polymerization process might be another

reason for the non-uniform cell size of the flexible foam [26].

The rigid foam displayed closed cell structure with ~30 cells/mm2 and a cell size of

217± 24 µm which were higher compared to those of the rigid foams made from PMTAG

Polyol (density ~24 cells/mm2 and cell size 270 ± 40 µm [8]). This is attributable to the

high cross linking density promoted by lesser amount of saturated dangling chains in the

rigid foams made from the high hydroxyl LF-Polyol compared to the rigid PMTAG Polyol

292

5 c

m-1

227

0 c

m-1

Wavenumber (cm-1

)

100015002000250030003500

Ab

so

rba

nce

3344

cm

-1 292

5 c

m-1

RF

FF

227

0 c

m-1

284

8 c

m-1

172

5 c

m-1

151

1 c

m-1

141

4 c

m-1

148

foam. The flexible foam displayed a closed cell structure with cell size of ~330 ± 40 µm

and cell density (~15 cells/mm2) both smaller than those of the flexible foam made from

PMTAG Polyol (cell size ~386 ±55 µm, and density ~18 cells/mm2 [8]).

(a)

(b)

Figure 4.7. SEM images of rigid and flexible LF-Polyol foams: (a) rigid foam, (b)

flexibe foam

4.9.3 Thermal degradation Properties of LF-Polyol Foams

Figures 4.8 shows the DTG profiles of the rigid and flexible LF-Polyol foams. The

corresponding characteristic data are provided in the Appendix listed in Table A8. Both

the rigid and flexible foams prepared from LF-Polyol displayed thermal decomposition

profile comparable with other vegetable based polyol foams [21, 27, 28]. The DTG curves

of the rigid foam and flexible foam showed four prominent peaks (indicated by their peak

temperatures in Figures. 4.8) indicating a multi stage decomposition process. The weight

loss in the first step of the rigid foam degradation (21%) was higher than in the flexible

foam (17%) probably due to the higher amount of short urethane structures from low

molecular weight glycerol [29]. The decomposition peak around 300 °C involved a total

149

weight loss of ~17 to 21 % for the flexible and rigid respectively, and is related to the

dissociation of urethane bonds [29, 30]. The decomposition step in the range 360-430 °C

is associated with the degradation of the soft segments (polyol backbone) [30]. The soft

segments dissociate into carbon monoxide, carbon dioxide, carbonyls (aldehyde, acid,

acrolein), olefins and alkenes [18, 30]. This decomposition step involved the largest weight

loss with ~65% of the total. More strongly bonded fragments and carbonaceous materials

from the previous steps may have decomposed around 450 °C [8, 17].

Figure 4.8. (a) DTG of rigid (RF) and flexible (FF) LF-Polyol foams

Temperature (oC)

100 200 300 400 500

DT

G

(%

/oC

)

30

2 o

C

36

1 o

C

44

6 o

C

30

7 o

C

42

0 o

C

RF

FF

150

4.9.1 Thermal transition Properties of LF-Polyol Foams

Figure 4.9. DSC thermogram of rigid (RF) and flexible (FF) LF-Polyol foams

Figures 4.9 shows the DSC profiles obtained during the second heating cycle of the

rigid and flexible foam from LF-Polyol. The rigid and flexible foams displayed one

inflection point indicating a glass transition at ~ -21.4 °C and ~ -18.0 °C, respectively. The

glass transitions of the rigid and flexible foams are associated with the molecular motion

of the soft segments related to the polyols [31]. Unlike the rigid and flexible foams from

PMTAG Polyol [5], those made from LF-Polyol did not show a glass transition related to

the relaxation of the urethane segment. This may be due to the compact crosslink network

achieved by the foams due to the absence of saturated dangling chains in LF-Polyol.

4.9.2 Compressive Strength of LF-Polyol Foams

The compressive strength versus strain curves of the rigid and flexible foams are

shown in Figure 4.10a and 4.10b, respectively. The rigid and flexible foams displayed

relatively quick yielding up to 6% and 8%, respectively, followed by a plateau-like region

over which there is a little increase in stress with increasing strain. The initial region up to

Temperature (oC)

-40 0 40 80 120

Heat

Flo

w

(W

g-1

) Tg

RF

FF

151

~4% in case of the rigid foam and ~6% in case of flexible foam indicates their respective

elastic regions. The plateau-like region resulted from either the collapse or cell wall

buckling of the foams [24]. Further compression above 30% (Figure. 4.10b) in case of

flexible foams results in crushing of the cell wall and is referred to as the densification

region [24].

Figure 4.10. Compressive strength versus strain curves of (a) Rigid LF-Polyol foam

of density 163 kg/m3 (RF) and (b) Flexible LF-Polyol Foam of density 161 kg/m3 (FF).

Table 4.4. Compressive strength of LF-PMTAG Polyol Foams at different strain (%):

Rigid LF-Polyol Foam (RF), Flexible LF-Polyol Foam (FF); Rigid PMTAG Polyol Foam

(RF-PMTAG Polyol); and Flexible PMTAG Polyol Foam (FF-PMTAG Polyol)

Foams Density (kgm-3) Compressive strength (MPa)

@ Strain (%) 6 10

RF 163 1.19 1.29

RF-PMTAG Polyol 161 0.66 0.85

@ Strain (%) 10 25

FF 160 0.52 0.61

FF-PMTAG Polyol 164 0.69 0.83

Strain (%)

0 3 6 9 12 15

Com

pre

ssiv

e s

tre

ngth

(

MP

a)

0.0

0.4

0.8

1.2

1.6

RF

(a) (b)

Strain (%)

0 10 20 30 40 50

Com

pre

ssiv

e S

trength

(

MP

a)

0.0

0.4

0.8

1.2

1.6

FF

152

The compressive strength of rigid and flexible foams from LF-Polyol at selected

strain is presented in Table 4.4. The rigid foam (RF) displayed a higher compressive

strength than the rigid PMTAG Polyol foam (1.29 MPa compared to 0.85 MPa at 10%, as

seen in Table 4.4). This corroborates that the fractionation process was very effective in

removing the saturated chains from LF-PMTAG, leading to LF-Polyol with much less

pendant chains, which resulted in a higher compressive strength of the rigid foams.

Although LF-Polyol presented a higher OH value than PMTAG Polyol, the flexible foam

from LF-Polyol (FF) displayed a lower compressive strength (see Table 4.4) than the

flexible PMTAG Polyol foam (FF-PMTAG Polyol) because of the higher percentage of

terminal hydroxyls in PMTAG Polyol (~24.1 mol%) compared to the LF-Polyol (~20

mol%).

Figure 4.11. Recovery of LF-Polyol Flexible Foam (FF) as a function of time (min)

Figure 4.11 shows the percentage of recovery in thickness of flexible foams (FF) as

a function of time. The recovery in thickness of the flexible foams were measured after its

maximum compression (65%) using a Vernier caliper. The recovery in thickness was

Time (min)

0 3 6 9 12 15 15003000

Recovery

(

%)

0

20

40

60

80

100

FF

153

recorded every minute for the first ten minutes, then after 1, 2, 24 and 48 h. More than 80%

recovery was obtained in less than 2 min. Similar like FF-PMTAG Polyol, the FF also

showed a good recovery, which substantiates its suitability for flexible foam applications.

4.10 Conclusions

The fractionation by dry and solvent mediated crystallization was demonstrated to

effectively remove the non-functional saturated triacylglycerols (TAGs) of PMTAG. The

fatty acid profile of the fractions of PMTAG was reflected in the chemical characteristics

such as iodine value and physical properties such as the thermal phase transitions. The

liquid fraction (LF-PMTAG) which was devoid of the saturated TAGs and enriched in

unsaturated fatty acid moieties displayed an onset temperature of crystallization 15 °C

lower than the solid fraction (SF-PMTAG) which retained the trisaturated TAGs and some

of the partially unsaturated TAGs. Its onset of crystallization was 11 °C lower than that of

PMTAG also. However, LF-PMTAG possessed a lower percentage of terminal double

bonds compared to PMTAG, probably because these were predominantly found in TAGs

with long saturated fatty acid moieties that were selectively filtered with the solid fraction.

Also, the molar percentage of oleoyl type molecules, with internal double bonds, was

higher in LF-PMTAG compared to PMTAG and SF-PMTAG probably because of its

higher content of tri, dioleoyl type of TAGs as well as their combination with short fatty

acids moieties.

Because the epoxidation and hydroxylation reaction was complete, the polyols

synthesized from LF-PMTAG and SF-PMTAG consisted of diols, tetrols and hexols with

terminal and internal hydroxyl molecules that matched the composition of the starting

fraction. Expectedly, the polyol produced from LF-PMTAG (LF-Polyol) presented an OH

154

value (184 mg KOH/g) that is higher than polyol made with SF-PMTAG (SF-Polyol, 136

mg KOH/g ) and PMTAG Polyol (155 mg KOH/g), the polyol synthesized from the non-

fractionated PMTAG. LF-Polyol presented a melting point at ~45 °C, and a relatively low

viscosity when liquid, all characteristics suitable for the processing and transformation of

the polyol into polyurethane foams using normal polymerization conditions and existing

equipment.

The OH value, melting point and viscosity profile of LF-Polyol allowed the

preparation of rigid as well as flexible foams having enhanced physical and structural

properties. The rigid foam prepared from LF-Polyol for example displayed a compressive

strength more than 50% higher than the rigid foam made from PMTAG. Also, the quality

of the flexible foam made from LF-Polyol as estimated with the compressive strength and

recovery measurements was measurably higher than that of the flexible PMTAG Polyol

foam. The closed cell structure of both the rigid and flexible foams, as shown by SEM,

indicates that they are suitable for structural and thermal insulation applications.

The study demonstrate that the fractionation technology can be used to custom design

PMTAG feedstocks with controlled iodine value and varied distribution of unsaturation,

position of the double bonds and chain length using existing equipment. It was also

demonstrated that polyols with high OH value, and suitable melting and viscosity profiles

can be synthesised from such feedstocks, and that enhanced rigid as well flexible

polyurethane foams can be easily produced without the need for specialized infrastructure,

equipment or technology.

155

4.11 References

[1] Braipson‐Danthine S, Gibon V. Comparative analysis of triacylglycerol composition,

melting properties and polymorphic behavior of palm oil and fractions. European Journal

of Lipid Science and Technology. 2007;109(4):359-72.





Society. 2007;84(1):65-72.



[5] Prasanth S. Pillai LB, Shaojun Li and Suresh S. Narine. 1-Butene Metathesized Palm

Oil & Polyol Derivatives: Structure, Chemical Composition and Physical Properties.

Submitted to Industrial Crops and Products. 2015.

[6] Mol J. Catalytic metathesis of unsaturated fatty acid esters and oils. Topics in Catalysis.

2004;27(1-4):97-104.



[8] Prasanth S. Pillai SL, Laziz Bouzidi and Suresh S. Narine Water-Blown Bio-Based

Polyurethane Foams from 1-Butene Metathesized Palm oil Polyol. Submitted to Industrial

Crops and Products. 2015.

[9] Hamm W. Trends in edible oil fractionation. Trends in Food Science & Technology.

1995;6(4):121-6.

[10] Timms RE. Fractional crystallisation- the fat modification process for the 21 st

century. European Journal of Lipid science and Technology. 2005;107(1):48-57.

[11] Dunn RO. Improving the cold flow properties of biodiesel by fractionation: INTECH

Open Access Publisher, 2011.

[12] Kellens M, Gibon V, Hendrix M, De Greyt W. Palm oil fractionation. European

Journal of Lipid Science and Technology. 2007;109(4):336-49.

[13] Ramli M, Siew W, Cheah K. Properties of High‐Oleic Palm Oils Derived by Fractional

Crystallization. Journal of Food Science. 2008;73(3):C140-C5.

[14] Hasmadi M, AINI I, Mamot S, Yusof M. The effect of different types of stirrer and

fractionation temperatures during fractionation on the yield, characteristics and quality of

oleins. Journal of Food Lipids. 2002;9(4):295-307.

156

[15] Tan C, Man YC. Differential scanning calorimetric analysis of palm oil, palm oil based

products and coconut oil: effects of scanning rate variation. Food Chemistry.

2002;76(1):89-102.

[16] Zaliha O, Chong C, Cheow C, Norizzah A, Kellens M. Crystallization properties of

palm oil by dry fractionation. Food Chemistry. 2004;86(2):245-50.





[19] Prasanth S. Pillai SL, Laziz Bouzidi and Suresh S. Narine. Solvent Free synthesis of

Polyols from 1-Butene Metathesized Palm Oil for Use in Polyurethane Foams. Submiited

to Journal of Applied Polymer Science. 2015.

[20] Dai H, Yang L, Lin B, Wang C, Shi G. Synthesis and characterization of the different

soy-based polyols by ring opening of epoxidized soybean oil with methanol, 1, 2-

ethanediol and 1, 2-propanediol. Journal of the American Oil Chemists' Society.

2009;86(3):261-7.


rigid polyurethane foam. The Journal of The Minerals, Metals & Materials Society.

2007;17:7-23.





2007;84(2):173-9.



2012;89(11):2103-11.

[25] Szycher M. Handbook of polyurethanes. CardioTech International Inc., Woburn, MA

(US); 1999.



[27] Ravey M, Pearce EM. Flexible polyurethane foam. I. Thermal decomposition of a

polyether‐based, water‐blown commercial type of flexible polyurethane foam. Journal of

Applied Polymer Science. 1997;63(1):47-74.

157








foams using a palm oil-based polyol. Bioresource technology. 2008;99(9):3810-6.

158

5 Solvent Free Synthesis of Polyols From 1- Butene

Metathesized Palm Oil for Use in Polyurethane foams3

5.1 Introduction

Polyurethanes (PU) are versatile polymers which have traditionally been

manufactured from petroleum [1]. The range of polyurethane products includes

polyurethane elastomers [2], sheets [2], adhesives [3], coatings [4] and foams [2], spanning

uses across a large array of industries and products. With a market of $82.6 billion in 2012,

PU foams have the largest market share of polymers, projected to reach $131.1 billion by

2018 [5]. PU can be prepared via two principal routes, in the step growth polymerization

of isocyanate (NCO) groups and hydroxyl groups [6] and with non-isocyanate pathways,

such as the reaction of cyclic carbonates with amines [7], self-polycondensation of

hydroxyl-acyl azides or melt transurethane methods [8].

Growing concerns surrounding sustainability, biodegradability, control of CO2

emissions and other environmental problems are driving a search for alternative feedstock

to petroleum. Vegetable oils and their derivatives are seen as good renewable materials for

the synthesis of polymer substrates, particularly for polyols used in PU production. A

3 Aversion of this chapter is filed as a US provisional patent: 2. U.S. Provisional Patent Application

#62109441, (filed January, 2015), “Metathesized Triacylglycerol Green Polyols from Palm oil for Use in

Polyurethane Applications and Their Related Physical Properties,” S.S. Narine, Prasanth. K. S. Pillai, S.Li,

and L. Bouzidi and Submitted for a publication in Journal of Applied Polymer Science

159

considerable body of work has been already published related to the synthesis of polyols

and polyurethanes from a variety of vegetable TAG oils such as soybean oil [9, 10],

safflower oil, corn oil, sunflower seed oil, linseed oil [11], rapeseed oil [12], and cotton

seed oil [13].

Palm oil presents a particularly interesting potential for industrial use as it is one of

the least expensive and most widely available oils (53 million metric ton in 2013: according

to the FAO) [14]. However, its high saturated fatty acid composition (50% of the total) and

the internal nature of its double bonds limit the potential use of palm oil in PU foam

formulations, particularly in rigid PU foams [15]. The internal location of the double bonds

results in polyol functionalization with secondary hydroxyl groups, which are less reactive

and lead to incomplete crosslinking during polymerization and imperfections in the

polymer network [2, 16]. The regions where dangling chains are present do not support

stress when the sample is under force, and act as plasticizers, reducing polymer rigidity

[17, 18].

Olefin cross metathesis of natural oils and fats is an important organic synthesis

technique that is used to produce fine chemicals, substrates and materials, many of which

serve as or are potential petrochemical replacements [16, 19-22]. The cross metathesis

reaction effectively shortens some of the unsaturated fatty acids of the TAGs at the

unsaturated sites, producing terminal double bonds [23, 24], which gives the potential of

producing polyols with primary hydroxyl groups, and therefore dramatically reduces

dangling chains in polyurethane networks[16, 25]. In addition, the composition of a

metathesized product can be controlled by varying the reaction conditions, such as starting

160

materials, temperature, type of catalyst, etc. [26-28] allowing for a large range of designer

materials.

The present work is part of research efforts targeted at investigating the potential of

metathesized vegetable oil products for the production of polyols for PU and other polymer

applications, and other useful materials. The starting material used in the present study is

a 1-butene cross metathesized palm oil (PMTAG) stripped of its olefins, provided by

Elevance Renewable Science (ERS). Its full chemical and physical characterization and its

conversion into polyols, using solvent-mediated processes, for the preparation of rigid and

flexible polyurethane foams have already been reported [29, 30]. Previously, polyols were

produced from PMTAG using epoxidation reactions, followed by a hydroxylation method

and involved the utilization of harsh and dangerous solvents like DCM and THF.

The present effort was targeted at the synthesis of polyols from PMTAG using green,

one pot solvent free epoxidation and hydroxylation pathways. The synthesis of green

polyols from soybean oil and castor oil by solvent free/catalyst free epoxidation for

polyurethane applications was previously reported [31]. The solvent free synthetic route is

not only safer and environmentally friendly, but also much more economical. The

epoxidation and hydroxylation reaction conditions were tuned to control the conversion of

PMTAG double bonds into hydroxyl groups and hence control the hydroxyl value of the

polyols. Four batches (B1-4) of these so-called Green Polyols were produced. The chemical

structure and composition of the polyols were characterized by 1HNMR, HPLC, OH value,

and Iodine value. Thermal stability, thermal transition behavior, and flow properties were

determined by TGA, DSC, and rotational rheometry, respectively. Rigid and a flexible

foams were prepared from the Green Polyols with OH values of 83 and 119 mg KOH/ g

161

respectively. The foams were characterized by FTIR and SEM. Their thermal stability,

thermal transition behavior, and compressive strength were investigated using TGA, DSC,

and a texture analyzer, respectively.


5.2.1 Materials

PMTAG was provided by Elevance Renewable Sciences (ERS, Bolingbrook, II).

Formic acid (88 wt %), Iodine monochloride (95%), potassium iodide (99%),

phenolphthalein, hydrogen peroxide solution (30 wt%), Dibutin Dilaurate (DBTDL) and

glycerin (99.5 %) were purchased from Sigma-Aldrich, Canada (Oakville, Ontario,

Canada). Perchloric acid (70%) and N, N-Dimethylethanolamine (DMEA were purchased

from Fisher Scientific, Canada. Ethanol (anhydrous), toluene, potassium hydroxide, and

sodium thiosulfate were purchased from ACP chemical Inc. (Montreal, Quebec, Canada).

All of the above compounds were used as received. Diphenylmethane diisocynate (MDI)

from Bayer Materials Science (Pittsburgh, PA), Polyether-modified surfactant

(TEGOSTAB B-8404) from Goldschmidt Chemical Canada. The properties of the MDI

are presented in Table A10 in the Appendix.

5.2.2 Chemistry Characterization

5.2.2.1 Titrimetric Methods (OH value, Acid value, Iodine value)

OH and acid values of the PMTAG Polyol were determined according to ASTM

S957-86 and ASTM D4662-03, respectively. Iodine value was determined according to

ASTM D5768-02.

162

5.2.2.2 Proton Nuclear Magnetic Resonance Spectroscopy (1HNMR)

1H-NMR spectra were recorded in CDCl3 on a Varian Unity-INOVA at 499.695

MHz. All spectra were obtained using an 8.6 μs pulse with 4 transients collected in 16 202

points. Datasets were zero-filled to 64 000 points, and a line broadening of 0.4 Hz was

applied prior to Fourier transformation. The spectra were processed using spinwork NMR

Processor, version 3. 1H chemical shifts are internally referenced to CDCl3 (7.26 ppm).

5.2.2.3 Gel Permeation Chromatography (GPC)

Molecular weights and distribution were determined by gel permeation

chromatography (GPC). The measurements were carried out on an e2695 GPC instrument

equipped with a Waters e2695 pump, Waters 2414 refractive index detector and a 5-µm

Styragel HR5E column (Waters Alliance, Milford, MA). Chloroform was used as eluent

with a flow rate of 0.5 mL/min. The concentration of sample was 1 mg/mL and the injection

volume was 10 µL. Polystyrene (PS) standards and pure TAG-oligomers (synthesized

previously [32]) were used for calibration. Waters Empower Version 2 software was used

for data collection and data analysis.

5.2.2.4 Fourier Transform Infrared Spectroscopy (FTIR)

The FTIR spectra of the foams were obtained with a Thermo Scientific Nicolet 380

FTIR spectrometer (Thermo Electron Scientific Instruments, LLC, USA) equipped with a

PIKE MIRacleTM attenuated total reflectance (ATR) system (PIKE Technologies,

Madison, WI, USA.). Solid samples were loaded onto the ATR crystal area, and sample

spectra were acquired over a scanning range of 400-4000 cm-1 for 32 repeated scans at a

spectral resolution of 4 cm-1.

163

5.2.3 Physical Characterization Techniques


TGA measurements were carried out on a TGA Q500 (TA Instruments, DE, USA)

equipped with a TGA heat exchanger (P/N 953160.901). Approximately 8.0 – 15.0 mg of

sample was loaded into the open TGA platinum pan. The sample was heated at a constant

rate of 10 °C/min from 25 to 600 °C under dry nitrogen. The “TA Universal Analysis”

software (TA Instruments, New Castle, DE) was used to analyze the TGA curves.


DSC measurements were performed on a Q200 model (TA Instruments, New Castle,

DE) under a nitrogen flow of 50 mL/min.

Polyol samples between 3.5 and 6.5 (± 0.1) mg were run in standard mode in

hermetically sealed aluminum pans. The sample was equilibrated at 90 °C for 10 min to

erase thermal memory, and then cooled at 5.0 °C/min to -90 °C where it was held

isothermally for 5 min and subsequently reheated at a 5.0 °C/min to 90 °C.

Foam samples between 3.0 and 6.0 (± 0.1) mg were run in modulated mode in

hermetically sealed aluminum DSC pans. The sample was first equilibrated at 25 °C and

heated to 150 °C at 10 °C/min (first heating cycle). The sample was held at that temperature

for 10 min and then cooled to -90 °C at 10 °C/min, where it is held isothermally for 5 min

and subsequently reheated to 150 °C at the same rate (second heating cycle). The

modulation amplitude and period were ±1 °C and 60 s, respectively.

164

The “TA Universal Analysis” software was used to analyze the DSC thermograms.

The characteristics of non-resolved peaks were obtained using the first and second

derivatives of the differential heat flow.

5.2.3.3 Rheology

The flow behavior and viscosity versus temperature of the polyols were measured on

a temperature controlled Rheometer (AR2000ex) using a 40-mm, 2° steel geometry.

Temperature control was achieved by a Peltier attachment with an accuracy of ~0.1 °C.

Shear stress versus shear rate curves were measured at 10 °C intervals from high

temperature (100 °C) to ~ 10 °C below the DSC onset of crystallization temperature. The

viscosity versus temperature data were collected at constant shear rate (200 s-1) using the

ramp procedure while the sample was cooling (1.0 and 3.0 °C/min) from ~110 °C to just

above the crystallization point. Data points were collected at 1 °C intervals.




0

nK Eq. 5.1

Where denotes the shear stress, 0 is the yield stress below which there is no flow, K

the consistency index and n the power index. n depends on constitutive properties of the

material. For Newtonian fluids n = 1, and for shear thickening and shear thinning fluids

1n and 1n , respectively.

165

5.2.3.4 Texture Analysis

The compressive strength of the foams were measured at room temperature using

a texture analyzer (TA-TX HD, Texture Technologies Corp, NJ, USA). Samples were

prepared in cylindrical Teflon molds 60-mm in diameter and 36-mm in length. During

compressive force measurements, the cross head speed was 3.54 mm/min, recorded on a

750 Kgf load cell for both the rigid and flexible foams. The load was applied until the foam

was compressed to approximately 15% and 65% of the original thickness of the rigid and

flexible foams, respectively.

5.2.3.5 Scanning Electron Microscopy (SEM)

Composite SEM images of the foams were resolved with a Phenom ProX, (Phenom-

World, The Netherlands) scanning electron microscope at an accelerating voltage of 15 kV

and map intensity. Uncoated foams were cut into thin rectangular segments and fixed to a

temperature controlled sample holder with conductive tape. Samples were cooled to -25 °C

to prevent beam induced thermal deformations, and composite images were captured using

the Automated Image Mapping software (Phenom-World, The Netherlands).

5.2.4 Synthesis Methods

5.2.4.1 Epoxidation

2 kg PMTAG was added into 2 kg formic acid (88%) in a 20L reactor fitted with a

HAAKE Phoenix II temperature controlled circulator (Thermoscientific, Newington, NH).

The initial reaction temperature of the epoxidation was varied (Epx

iniT in Table 5.1)

depending on the batch. 2.8 L of hydrogen peroxide (30%) was added to the reactor slowly

(~1 L/h) while the reaction mixture was vigorously stirred. During addition of hydrogen

166

peroxide, the exothermic nature of the epoxidation reaction caused the temperature to

increase. In the case of Batch 3, the temperature controlled system wasn’t used, the

temperature of the reaction reached a maximum of 95 ºC but remained less than 10 min at

that temperature. Due to the exothermic nature of the epoxidation reaction, the temperature

of the other batches also increased ( max

EpxT in Table 5.1). Tap water was circulated to cool

Batch 4, and the control feature of the circulator was used to bring Batch 1 and Batch 2 to

the actual epoxidation temperature (Epx

RT in Table 5.1). The epoxidation reaction was

continued at Epx

RT overnight. The reaction mixture was finally washed with 2×1 L water,

1×1 L 5% NaHCO3 and 2×1 L water sequentially. The mixture was used for the next step

directly. Yield > 95 %.

Table 5.1. Epoxidation reaction temperature and time data for the synthesis of green

polyols. Epx

iniT : Initial temperature of the epoxidation reaction; max

EpxT : highest temperature

reached during the epoxidation reaction; Epx

RT : reaction temperature for epoxidation; Epx

Rt

: reaction time

Epoxidation

Batch Epx

iniT max

EpxT Epx

RT Epx

Rt

1 50 65 48 16 h at 45 ºC then 12 h at 48 ºC

2 40 49 48 16h at 48 ºC

3 25 95 45 16h at 45 ºC

4 25 48 25 16h at 25-48 ºC

167

5.2.4.2 Hydroxylation

The epoxide of PMTAG (2 kg) above was added into 10 L water, and then followed

by 140 g HClO4 (70%) with a ratio of PMTAG/H2O/perchloric acid = 1/5/0.05. The

reaction mixture was heated to ~ 85 °C and stirred at that temperature for 16 h after which

stirring and heat were ceased and the mixture sat at room temperature to aid in separation.

The organic layer was washed with 2×1 L water, 1×1 L 5% NaHCO3 and 2×1 L water

sequentially, and then dried on a rotary evaporator. Yield > 95 %.

5.2.4.3 Polymerization Method

Rigid and flexible polyurethane foams were prepared from B3- and B4-Green polyol

and MDI using a previously published method. The formulation recipes for the rigid and

flexible foams are presented in Table 5.2. The amount of each component was based on

100 polyol parts by weight. As shown in Table 5.2, the rigid foams were prepared based

on a total hydroxyl value of 450 mg KOH/g. In The case of the rigid foams, glycerin, a

poly hydroxyl cross linker, was added into the reaction mixture (20.1 and 18.1 parts for

B3- and B4-Polyol Rigid Foams, respectively) in order to obtain the targeted hydroxyl

value of 450 mg KOH/g (see Table 5.2).

The amount of MDI in both rigid and flexible foam formulations was adjusted to

achieve an isocyanate index of 1.2 (NCO to OH ratio of 1.2 to 1). Note that the NCO to

OH ratio in the rigid foam formulation includes the OH from the added glycerol.

The amount of cross linking catalyst DBTDL, which favors the gelling reaction, and

the co-catalyst DMEA, which functions as a blowing catalyst, were fixed at 1 and 0.5 parts

168

respectively based on the fairly good compressive strength previously obtained for rigid

polyurethane foams prepared from terminal hydroxyl polyols.

The cross linking catalyst DBTDL, which favors the gelling reaction, and the co-

catalyst DMEA, which functions as a blowing catalyst, were used for the polymerization

process. The choice of the catalyst ratios were fixed based on the fairly good compressive

strength previously obtained for rigid polyurethane foams prepared from terminal hydroxyl

polyols.

Table 5.2. Formulation Recipes for Rigid and Flexible Foams. Amounts are based

on 100 parts by weight of total polyol

Rigid Foams Flexible Foams

Ingredient Parts Parts

B3-Green Polyol or

B4-Green Polyol 100 100


Glycerin B3 20.1 0

B4 18.1 0

Water 2 2

Surfactant 2 2

Catalyst 1 0.5

Co-catalyst 1 0.5

All the ingredients except MDI were melt and weighed into a beaker and mixed for

10-20 s. The pre-measured MDI was then added into the beaker and stirred vigorously for

5 to 20 s and transferred into a cylindrical Teflon mold (60 mm diameter and 35 mm long)

which was previously greased with silicone release agent. The mold was then then sealed

with a hand tightened clamp and the sample was cured for four days at 40 ºC, with an

169

additional post curing of one day at room temperature. Table 5.2 gives the formulation

recipe used for the preparation of rigid and flexible polyurethane foams from B3- and B4-

Green Polyols.


5.3.1 Solvent Free Synthesis of Polyol from PMTAG

The Green Polyols were prepared from PMTAG in a solvent-free one-pot two-step

reaction; epoxidation by formic acid and hydrogen peroxide (H2O2), followed by

hydroxylation using perchloric acid (HClO4) as the catalyst, as described in Scheme 5.1.

The formic acid (88%)/H2O2 (30%)/PMTAG ratio was kept at 1/1.4/1 and

PMTAG/H2O/perchloric acid at 1/5/0.05 in all the batches. The epoxidation conditions

(temperature and time) were adjusted in order to optimize the reaction, control the OH

value, and to manage the amount of formic acid that can become attached to the polyol.

The temperature and time of the four different batches of epoxidation reactions were tuned

so as to control the conversion of the double bonds into epoxides (see Table 5.1). The

controlled double bond conversion subsequently enables the production of polyols with

controlled hydroxyl value. Note that when the temperature was below 70 ºC, the degree of

epoxidation in the melt was limited (~80 to 90 % conversion of total double bonds). Also,

at temperatures higher than 50 °C, the epoxide was opened by formic acid and formic acid

units were found attached to some of the polyol backbones. Therefore, in order to avoid

formic acid units attached to the polyol backbone, the epoxidation temperature should be

kept below 50 ºC. The hydroxylation of all the batches was run at 85 °C over 16 h. The

Green Polyols obtained from the four batches are labelled B1 – B4-Polyol.

170

Scheme 5.1. Solvent-free synthesis of polyols from PMTAG. n= 0, 2, 8; m= 11 to

20.

5.3.2 Chemical Characterization and Compositional Analysis of PMTAG Green

Polyols

The structure of the epoxides was confirmed by 1H-NMR. The characteristic

chemical shift values of the specific protons of B1-, B2-, B3- and B4-epoxy PMTAG are

provided in Appendix in Table A11. The chemical shift at 2.85 ppm, related to the non-

terminal epoxy ring, and the chemical shift at 2.7 to 2.4 ppm related to the terminal epoxy

ring appeared for the epoxidized PMTAG of all the batches, indicating that the epoxidation

171

reaction was successful. However, although the chemical shift at 5.4 ppm related to internal

double bonds disappeared, peaks at 5.0 to 4.8 ppm were still present, indicating that the

terminal double bonds were not completely converted into epoxides.

The relative amount of remaining terminal double bonds (RTDB) as estimated by

1H-NMR for each batch of epoxy PMTAG is provided in Table 5.3. Note that RTDB

(mol%) was calculated as the ratio of remaining terminal double-bonds in the PMTAG

epoxide to the terminal double bonds in the starting PMTAG material. The chemical shift

at δ 8 ppm indicating the presence of formic acid attached to the backbone of the epoxide

was present in the epoxidized PMTAG of B1 and B2 but not B3 and B4. The number of

formic acid units per TAG epoxide, as estimated by 1H-NMR, is provided in Table 5.3.

The structure of the Green Polyols (B1 to B4) were confirmed by 1H-NMR. Figures

A11 in the Appendix show the 1H-NMR spectra of B1-B4 Green Polyols, respectively. The

corresponding 1H-NMR chemical shifts in CDCl3 are listed in Table A12. The spectra of

all the polyols presented the chemical shift related to protons neighbored by –OH (at 3.8-

3.4 ppm) but not the chemical shift related to epoxy rings (at 2.8-2.4 ppm) indicating that

the hydroxylation reaction was complete. The Green Polyols presented the typical chemical

shift related to a glycerol skeleton: -CH2CH(O)CH2- at δ 5.3-5.2 ppm, -

OCH2CH(O)CH2O- at 4.4-4.1 ppm, -C(=O)CH2- at δ 2.33-2.28 ppm, and -C(=O)CH2CH2-

at δ 1.60 ppm. The peak areas of chemical shifts at 4.4 - 4.2 ppm and at 4.2 to 4.0 ppm

were equal, indicating that hydrolysis of the TAGs was avoided. Because the epoxidation

of the terminal double bonds was not complete, the Green Polyols also showed chemical

shifts of the remaining terminal double bonds (-CH=CH2 at 5.8 ppm, and –CH=CH2 at 5.0-

4.8 ppm). The formic acid units on the backbone (chemical shift at δ 8 ppm) were presented

172

in B1- and B2-Polyols but not in B3- and B4-Polyols, similar to their starting epoxides.

The RTDB (mol%) of the Green Polyols and the number of formic acid units per TAG

polyol are listed in Table 5.3.

Table 5.3. Amount of remaining terminal double bonds (RTDB)1, number of formic

acid units per TAG polyol and terminal OH groups as estimated by 1H-NMR. Iodine value,

Acid value and OH number of PMTAG Green Polyols.

Green PMTAG

Epoxides

Green Polyols

Batch RTDB

(mol%)

Formic

acid

units

per

TAG

RTDB

(mol%)

Terminal

OH group

(mol%)

Iodine

Value

OH Value

(mg

KOH/g)

Acid Value

(mg

KOH/g)

B1 25.0 0.14 25.0 18.7 5 113 5

B2 26.0 0.14 26.0 18.5 7 117 1.3

B3 34.0 0.00 34.0 16.6 9 83 1.3

B4 27.0 0.00 27.0 18.3 8 119 1.3

1Remaining terminal double bonds (RTDB%) was calculated as the ratio of remaining

terminal double-bonded fatty acids in Green Polyol to the terminal double bonded fatty

acids in PMTAG

The solvent free synthetic strategy adapted (see section 2.5) was very successful for

the synthesis of Green Polyols with controlled OH values. It was also confirmed in the

1HNMR characterization of the epoxides and polyols that the controlled reaction

parameters such as Epx

iniT and Epx

RT (see Table 5.1) facilitated the avoidance of formic acid

units attached on the epoxide backbone in batches B3 and B4. Also the polyols produced

from the resultant epoxides such as B3-Green Polyol and B4-Green Polyol were completely

173

free from formic acid residuals. The Green Polyols presented OH values between 83 to

119 mg KOH/g (Table 5.3) and very low acid values, except for B1-Green Polyol which

displayed a relatively high acid value due to its longer epoxidation reaction time. Although

the OH values achieved using the green route are relatively lower compared to those of the

PMTAG Polyols prepared previously with solvents [29], they are large enough to make

suitable monomers for the preparation of flexible as well as rigid foams. B3- and B4- Green

Polyols which displayed very low acid values, no formic acid attached and significantly

different OH values (83 and 119 mg KOH/g respectively) were chosen for further physical

characterizations, and used for the preparation of rigid and flexible polyurethane foams.

The GPC of the B3- and B4-Green Polyols (the GPC data are provided in the

Appendix in Figure A12 and Table A13) revealed the presence of relatively important

levels of oligomers in the polyols. These include high molecular weight (Mw: 7030 g/mol)

oligomers as well as low molecular weight (Mw: 1463 g/mol) oligomers. B3- and B4-

Green Polyols comprised 45% and 37% oligomers, respectively, compared to 13%

oligomers in PMTAG Polyol. The higher oligomerization during the solvent free reaction

was due to its higher reaction temperature [33].

The composition of the PMTAG Green Polyols was determined with the help of 1H-

NMR and HPLC analyses of the column chromatographic fractions of B4-Polyol. Seven

different fractions (labelled F1 to F7) were obtained with ethyl acetate and hexanes as the

solvents. Column chromatography, 1H-NMR and HPLC data are provided in in the

Appendix in Table A14.

174

Scheme 5.2. General structures in PMTAG Green Polyol (n= 0, 2, 8; m= 11 to 20)

The 1HNMR of F1 did not present the chemical shift at 3.6-3.2 ppm which is related

to OH groups indicating that it is not the hydroxyl derivative. Also, F1 presented ~ 24

mol% unreacted terminal double bonds. F2 and F3 presented hydrolyzed TAG structures

formed during the hydroxylation reaction. The 1HNMR of F4, F5 and F6 presented

chemical shifts at δ 5.3-5.2 ppm and 4.4-4.1 ppm of -CH2CH(O)CH2- and -

OCH2CH(O)CH2O- of the glycerol skeleton, respectively, and at δ 3.8-3.4 ppm of the

proton neighboring hydroxyl groups indicating the presence of TAG diols and TAG tetrols.

F4, F5 and F6 presented also some unreacted terminal double bonds (~10 mol%) as

revealed by the chemical shifts at 4.8-5.0 ppm. Fraction F7 presented only tetrols (as

revealed by the chemical shift at δ 3.8-3.4 ppm, with ~ 15 mol% unreacted terminal double

bonds.

175

The 1HNMR results were confirmed and complemented by HPLC. The general

structures of the green polyols resulting from these analyses and based on structures of

PMTAG itself [29] are presented in Scheme 5.2.

5.3.3 Physical Properties of PMTAG Green Polyols

5.3.3.1 Thermogravimetric Analysis of Green PMTAG Polyols

As indicated by the DTG profiles of B3- and B4-Green Polyols shown in Figure 5.1,

B3- and B4-Green Polyols presented similar traces indicating a two-step degradation

process. The large DTG peak at ~380 ºC (TD1 in Figure 5.1) is associated with the

breakage of the ester bonds [34]. This dominant step which was initiated at 240 °C and

concluded at ~ -420 °C involved ~ 60% of weight loss. The small DTG shoulder peak at ~

450 °C (TD2, in Figure 5.1) is related to the decomposition of the ester groups and other

fragments, and the degradation of the remaining carbonaceous materials from the previous

step [35]. The onset of degradation of B3- and B4-Green Polyols as determined at 10%

weight loss ( 10%

dT ) was higher than 310 ºC, indicating a good thermal degradation stability

for the Green Polyols, comparable to other vegetable based polyols. Note that 10%

dT of

B4-Green Polyol was relatively smaller compared to B3-Green Polyol (12 ºC lower)

probably due to the loss of terminal hydroxyls which content is higher in B4-Green Polyol

[35].

176

Figure 5.1. DTG profiles of B3- and B4-Green Polyols

5.3.3.2 Crystallization and Melting Behavior of PMTAG Green Polyols

The crystallization and heating profiles (both at 5 °C/min) of B3- and B4-Green

Polyols are shown in Figure 5.2a and 5.2b, respectively. The corresponding thermal data

is listed in the Appendix in Table A15. as can be seen in Figure 5.2, B3- and B4-Green

Polyols present similar crystallization and heating behaviors with marked separation of a

high and low temperature events inherited from the PMTAG similarly to the PMTAG

Polyol synthesized via solvent mediation [29]. The difference between B3- and B4- Green

Polyol manifested in a small difference in their onset temperature of crystallization (26 °C

and 29 °C, respectively) and offset temperature of melting (48 °C and 50 °C, respectively).

Note that these values are consistent with the fact that B3-and B4-Green Polyols were not

liquid at ambient temperature. The large difference in their OH values was not reflected in

either the crystallization or melting traces, indicating that other structural attributes such as

remaining double bonds and short chain moieties played a counter effect. The melting point

of the Green Polyols as determined by the offset temperature of melting is ~2 ºC higher

DT

G

(%

oC

-1)

Temperature (oC)

100 200 300 400 500

0.0

0.5

1.0

1.5

2.0

B3

B4

TD1

TD2

177

than what was measured for the PMTAG Polyol synthesized via solvent mediation [29].

This may be due to the higher percentage of oligomers in the Green Polyols.

Figure 5.2. DSC thermograms of B3-, and B4-Green Polyols obtained during (a) Cooling,

and (b) subsequent heating (5 °C/min).

The heating thermogram of the Green Polyols displayed two groups of endothermic

events (G2 below 30 C, and G1 above 30 C in Figure. 5.2b) corresponding to the melting

of a high and low melting portions of the polyols. the enthalpy of melting of G1 and G2

(~26 J/g and ~66 J/g, respectively) was very similar to the enthalpy of P1 and P2,

respectively, suggesting that they are effectively the recording of the melting of the “high”

and “low” melting portions of the polyol, respectively. These DSC data indicate that with

careful processing, it is possible to separate PMTAG Polyol into two fractions: one mainly

constituted of low melting components, and another mainly constituted of high melting

components. It is expected that at ambient temperature, one fraction will be solid and the

other will remain liquid.

(a)

Temperature (oC)

-60 -30 0 30 60

Heat

Flo

w

/W

g-1

(Exo u

p)

0.0

0.2

0.4

0.6

0.8 P1

B3

B4

P2

(b)

Temperature (oC)

-30 0 30 60

Heat

Flo

w

/W

g-1

(Endo d

ow

n)

-0.6

-0.4

-0.2

0.0

B3

B4

G2

G1

178

5.3.3.3 Flow Behavior and Viscosity of B3-and B4- Green Polyols

Selected shear stress versus shear rate curves recorded for B3-, B4-Green Polyols

at selected temperatures are shown in Figures. 5.3a and 5.3b respectively. Fits to the

Herschel-Bulkley model (Eq. 5.1) are included in the figures (dashed lines in Figures. 5.3a

and 5.3b). Evident from Figure. 5.3, shear rate – shear stress curves were linear for the

entire range at temperatures from 40 °C to 90 °C for B3-Green Polyol and at temperatures

from 50 ºC to 90 ºC for B4-Green Polyol indicating Newtonian behavior. Application of

Eq. 5.1 to the share rate – shear stress data generated power index values ( n ) close to

unity and no yield stress (straight lines in Figure. 5.3, R2> 0.99999). The deviation from

the Newtonian behavior above 200 s-1 at 30 °C for B3-Green Polyol and above 400 s-1 at

40 °C for B4-Green Polyol is due to the close proximity to the onset temperature of

crystallization. Since their onsets of crystallization are closer than the temperatures at

which their flow was Newtonian, the difference in flow behavior between B3-and B4-

Green Polyols is attributed to the difference in OH value and terminal hydroxyls content

which were higher in B4-Green Polyol.

The viscosity versus temperature curves of B3- and B4-Green Polyols (Figure. 5.4)

presented the typical exponential behavior of liquid hydrocarbons [36, 37]. The viscosity

of the B4- Green Polyol was higher than that of B3-Green Polyol at all temperatures due

to a higher number of hydroxyl groups which increases the polarity and intermolecular

attractive force between the molecules by hydrogen bonding [38].

179

Figure 5.3. Shear rate- shear stress of PMTAG Green Polyols. (a) B3-Green Polyol

(b) B4-Green Polyol, respectively.

Figure 5.4. Viscosity versus temperature curves obtained during cooling (1 °C/min)

of B3-Green Polyol (empty circles) and B4-Green Polyol (empty triangles). Dashed lines

are guides for the eye.

The Green Polyols presented a slightly higher viscosity compared to the PMTAG

Polyol prepared using solvents [29]. This is explained by the presence of more oligomers

in the B3- and B4-Green Polyols (37 and 45 %, respectively compared to 13% in PMTAG

Temperature (oC)

40 60 80

Vis

cosity

(P

a.s

)

0.0

0.2

0.4

0.6

0.8 B3

B4

180

Polyol) formed during their hydroxylation step at 85 °C. The viscosities of the Green

Polyols are close to the range of viscosities of other polyols prepared from highly

unsaturated vegetable oils that are currently used in polyurethane applications [33, 39-41].

5.3.4 Polyurethane Foams

One rigid and one flexible foam were prepared from B3- and B4-Green Polyols using

a previously reported polymerization method [30]. As can be seen in Figure 5.5, the

polyurethane foams presented a smooth surface and a light yellow color. Note that the

catalyst amount for flexible foam formulation was fixed (0.5 parts, see Table 5.2), chosen

to avoid the cracks observed during the compression of the flexible foams made with

smaller catalyst concentrations.

(a) B3-RF145 (b) B3-FF162 (c) B4-RF166 (d) B4-FF156

Figure 5.5: Pictures of rigid and flexible foams from B3-and B4-Green PMTAG Polyols.

(a) B3-Green Polyol rigid foam of density 145 kgm-3 (B3-RF145), (b) B3-Green Polyol

flexible foam of density 162 kgm-3 (B3-FF162), (c) B4-Green Polyol rigid foam of density

166 kgm-3 (B4-RF166).and (d) B4-Green Polyol flexible foam of density 156 kgm-3 (B4-

FF156)

5.3.4.1 FTIR of B4-Green Polyol Foams

The FTIR spectra of the rigid and flexible foams produced from both B3- and B4-

Green Polyol confirmed the formation of urethane linkages. As shown in Figure 5.6,

181

representing the FTIR spectra of B4-flexible and a rigid foams typical of all the foams, the

characteristic absorption band of NH groups, C=O and C-N bonds which are associated

with the urethane linkage were presented at 3300-3400 cm-1, 1700 cm-1 and at 1516 cm-1,

respectively, (Figure 5.6) [42, 43]. However, as indicated by the weak band at 2270 cm-1

of the NCO group, some of the isocyanate did not react with the polyol [17, 42]. The

overlapping peaks between 1710 and 1735 cm-1 suggest the presence of urea and

isocyanurates in the foams. The peak at ~1410-1420 cm-1 reveals the presence of

isocyanurate trimers, indicating the occurrence of trimerization reactions of the

diisocyanates during the foaming process. The stretching bands of the ester groups are

particularly visible at 1744 cm-1 (C=O), 1150-1160 cm-1 (O-C-C) and 1108-1110 cm-1 (C-

C(=O)-O). The stretching vibration of -C-H in -CH3 and -CH2 groups in the aliphatic chains

are also visible at 2917-2925 cm-1, and 2850 cm-1 respectively [44]. The CH2 stretching

vibration and CH2 bend are also clearly visible at 2800-3000 cm-1 and 1030-1050 cm-1,

respectively [17].

Figure 5.6. Typical FTIR spectra of rigid (RF) and flexible (FF) B4-Green Polyol

foam.

Wavenumber (cm-1)

800160024003200

Absorb

ance

0.0

0.1

0.2

0.3

3340 c

m-1

2270 c

m-1

1730 c

m-1

1516 c

m-1

2917 c

m-1

1420 c

m-1

2850 c

m-1

RF

FF

182

5.3.4.2 SEM Analysis of Green Polyol Foams

Figures 5.7a, 5.7b and 5.7c, 5.7d show SEM images of the rigid and flexible foams

prepared from B4- and B3-Green Polyol, respectively. The cell structures of Figures 6a-d

are typical of all the rigid and flexible foams prepared in the present work. The

characteristics of the cell structure such as number and size of the cells was determined

from the analysis of all the visually separate cells of at least two specimens of each foam.

The values provided here are the subsequent calculated average and standard deviations.

The Green Polyol rigid foam displayed compact and uniformly distributed cells (B4: 450

± 44 µm, B3: 475± 60 µm). On the other hand, although with a somewhat similar average

cell size (B4: 494±145 µm, B3: 500 ±190 µm) the Green Polyol flexible foam presented a

heterogeneous cell structure with cell size ranging from 277 µm to 784 µm for B4 and 200

µm to 800 µm for B3. The stark differences in cell structure between the rigid and flexible

foams is attributable to the compounded effects of high cross linking density achieved by

the addition of glycerin in the rigid foam formulation and the different rates of crosslinking

of terminal and internal hydroxyls in the Green polyol flexible foam formulation [45].

Since both rigid and flexible foams only contain closed cells, they may also have

applicability in thermos insulation applications.

Both the rigid and flexible foams prepared from the PMTAG Green Polyols

displayed a smaller number of cells and larger cell size than the rigid and flexible foams

from PMTAG Polyol prepared via solvent mediation [30]. Beside the OH value and

terminal OH group effects considerations (OH value 119 mg KOH/g and 18.3% terminal

hydroxyl in the B4-Green Polyol for example vs. OH value of 155 mg KOH/g and 24.1%

terminal hydroxyl groups in the polyol prepared via solvent mediation), the larger amount

183

of oligomers in the Green Polyol (37% in B4-Green Polyol) may have added an extra

contribution for the larger size of cells of the rigid and flexible Green Polyol foams.

(a) (b)

(c) (d)

Figure 5.7. SEM micrographs of (a) B4-Green Polyol rigid foam, (b) B4-Green

Polyol flexible foam, (c) B3-Green Polyol rigid foam and (d) B3-Green Polyol flexible

foam

184

5.3.4.3 Thermal Stability of PMTAG Green Polyol Foams

As exemplified in Figure 5.8 showing the DTG profiles of B4-Green Polyol rigid

and flexible foams, the foams produced with the Green Polyols degraded following a multi

stage process. The first peak centered at 296-300 °C ( 1DT in Figure.5.8) is related to the

dissociation of urethane bonds that has taken place either through the dissociation of the

isocyanate and alcohol or to the formation of primary or secondary amines, olefin and

carbon dioxide [46, 47]. This first step involved a total weight loss of ~12 to 17 %. The

second and third decomposition steps signaled with the DTG peaks at ~ 370 and 420 °C (

2DT and 3DT in Figure 5.8) are associated with the decomposition of the soft segments

[47]. The soft segment (polyol back bone) dissociates into carbon monoxide, carbon

dioxide , carbonyls (aldehyde, acid, acrolein) olefins and alkenes [34, 47]. These two

decomposition steps involved the largest loss with 65% - 80% of the total weight. The last

step of degradation is signaled with the DTG peak at ~ 460 °C ( 4DT in Figure 5.8) and is

related to the decomposition of more strongly bonded fragments associated with the polyol

backbone that occur at high temperature, and probably to the degradation of remaining

carbonaceous materials from the previous step.

Note that the onset temperature of degradation of the rigid foam whether determined

at 5 or 10% weight loss was consistently lower (~16 ºC) than that of the flexible foams.

This can be due to the degradation of short chain urethane structures from the glycerin

cross linker.

185

Figure 5.8. DTG curves of B4-Green Polyol rigid foam (B4-RF) and B4-Green

Polyol Flexible Foam (B4-FF).

5.3.4.4 Thermal Transition of Green Polyol Foams

DSC analysis was carried out on the rigid and flexible foams produced with B4-

Green Polyol to study the thermal phase transition behavior of the Green Polyol foams.

Figure 5.9 shows the DSC profiles obtained during the second heating cycle of rigid and

flexible B4-Green Polyol foams respectively. One can notice that the thermogram of rigid

B4-Green Polyol foam presents two inflection points indicating two glass transitions (

lowTg (arrow 1 in Figure 5.9) at ~-12 °C and highTg (arrow 2 in Figure 5.9) at ~ 49 °C of

B4-RF in Figure 5.9) whereas B4-Green Polyol flexible foam thermogram shows three

inflection points indicating three glass transitions ( gLowT at - 11 °C, intTg at ~ 34 °C and

highTg at ~46 °C of B4-FF , arrow 1, 2 and 3 in Figure. 5.9).

Temperature (oC)

0 100 200 300 400 500 600

DT

G

(%

oC

-1)

0.0

0.4

0.8

1.2

B4-FF

B4-RF

300 o

C295 o

C

368 o

C

421 o

C

456 o

C

186

Figure 5.9. DSC heating thermogram (2nd cycle) of the B4-Green Polyol rigid (B4-

RF) and flexible foams (B4-FF): arrow 1 indicates lowTg , arrow 2 indicates intTg and

arrow 3 indicates highTg .

highTg of both the rigid and flexible Green Polyol Foams is attributable to the

relaxation of the urethane segments and their lowTg to the molecular motion of the soft

segments related to the polyols [48]. The glass transition observed at intermediate

temperature ( intTg ) in the flexible Green Polyol Foam is probably due to the relaxation of

the short chain urethane segments resulting from the Green Polyol mixture.

5.3.4.5 Compressive Strength of Green Polyol foams

The compressive strength of rigid foams prepared from B3-Green Polyol (density

145 kgm-3, B3-RF145), and B4-Green Polyol (density 166 kgm-3, B4-RF166), and flexible

foams from B3-Green Polyol (B3-FF162, density 162 kgm-3), and B4-Green Polyol (B4-

FF156, density 156 kgm-3) was characterized by the compressive stress-strain

measurements. Figure 5.10a and 5.10b show the compressive strength versus strain curves

Temperature (oC)

-60 -30 0 30 60 90

Heat

Flo

w

(W

g-1

)

-0.24

-0.20

-0.16

-0.12

-0.08 B4-RF

B4-FF

Tg low

Tg high

(1)

(2)(3)

(1)

(3)

187

of the examined rigid and flexible Green Polyol foams, respectively. The rigid and flexible

foams displayed relatively quick yielding followed by a plateau-like region over which

there was a little increase in stress with increase in strain. The elastic region was ~4% in

the case of rigid foams and 6% in case of flexible foams. Each region is determined by a

specific mechanism of deformation. Linear elasticity is controlled by cell wall bending,

and, in the case of closed cells such as in the case of the present foams, by stretching of the

cell walls [44]. The plateau-like region (above ~8% for the rigid foams in Figure 5.10a

and between 10 to 30% for the flexible foams in Figure 5.10b) results from either the

collapse or cell wall buckling of the foams [44]. Further compression of the flexible foams

above 30% resulted in and irreversible damage to the cell walls and is called the

densification region [44].

Figure 5.10. Compressive strength versus strain curves of (a) Rigid foams: B3-RF145

(B3-Green Polyol rigid foam of density 145 kgm-3), B4-RF166 (B4-Green Polyol rigid foam

of density 166 kgm-3) (b) Flexible foams. B3-FF162 (B3-Green Polyol flexible foam of

density 162 kgm-3), B4-FF156 (B4-Green Polyol flexible foam of density 156 kgm-3).

Strain (%)

0 2 4 6 8 10 12

Com

pre

ssiv

e s

trength

(

MP

a)

0.0

0.4

0.8

1.2B4RF-166

B3RF-145

(a)

Strain (%)

0 10 20 30 40 50

Com

pre

ssiv

e S

trength

(

MP

a)

0.0

0.4

0.8

1.2

B4FF-156

B3FF-162

(b)

188

Table 5.4 lists the compressive strength of rigid foams at 6% and 10 % deformation

and that of the flexible foams at 10% and 25% deformation. Even though both the B3- and

B4-Green Polyol rigid foams were prepared based on a total OH value of 450 mg KOH/g,

their compressive strength values were slightly different. The B3- and B4-Green Polyols

rigid foams displayed a higher compressive strength compared to PMTAG Polyol rigid

foam [30]. This may be due to the extra amount of highly reactive glycerol cross linker

added for the rigid foam formulation of B3- and B4-Green Polyol rigid foams to make for

the targeted OH value of 450 mg KOH/g. Four (4) and two (2 parts) of extra glycerol on

top of what was added to PMTAG Polyol were needed for the B3- and B4-Green Polyols,

respectively, to attain the same target OH value of the rigid foam formulations (see Table

5.2).

The compressive strength value of the rigid foams obtained from B3- and B4-Green

Polyols are higher than those prepared from natural TAG oil polyols such as, soybean oil

polyol[2] and canola oil polyol.[2] For example, the rigid B3- and B4-Green polyol foams

presented compressive strengths that are three (3) times larger than the 0.32 MPa of the

rigid foams prepared with polyol from soybean oil with the same density (~160 kg/m3),

understandably because the B3- and B4-Green polyols have lesser dangling chains and

relatively large amounts of primary hydroxyl groups contrary to the soybean oils which

presented internal hydroxyl groups only.

B3FF-162 and B4FF-156 displayed a significantly lower compressive strength than

the flexible foam of similar density 156 kgm-3 made from PMTAG Polyol. This is due to

the more marked effect of the difference in OH value of B3- and B4- Green Polyol (B3: 83

mg KOH/g and B4: 119 mg KOH/g compared to 155 mg KOH/g for PMTAG Polyol and

189

lesser percentage of terminal hydroxyls (B3: 16.5 mol% and B4: 18.3 mol % compared to

24.1 mol%) which become significant in the absence of the added glycerol.

Table 5.4. Compressive strength of rigid foams: B4-RF166 (B4-Green Polyol rigid

foam of density 166 kgm-3) versus RF-165 (PMTAG Polyol rigid foam of density 165 kgm-

3)at 6% and 10 % deformation. Flexible Foams: B3-FF162 (B3-Green Polyol flexible foam

of density 162 kgm-3), B4-FF156 (B4-Green Polyol flexible foam of density 156 kgm-3) and

FF-156 (PMTAG Polyol flexible foam of density 156 kgm-3) at 10% and 25% deformation.

Foams Density

(kgm-3)

Compressive strength

(MPa)

Recovery %: after

48h

Rigid Foams --

@ Strain (%) 6 10 --

B3-RF145 145 0.79 0.94 --

B4-RF166 166 0.72 1.05 --

RF 165 0.66 0.85 --

Flexible Foams --

@ Strain (%) 10 25 --

B3-FF162 162 0.21 0.30 94

B4-FF156 153 0.33 0.38 92

FF-156 156 0.69 0.88 80

The recovery in thickness of the flexible foam made from B4-Green Polyol (B4FF-

156) was measured after 65% compression at suitable times using a Vernier caliper. The

results are presented in Figure 5.11. As can be seen in the Figure 5.11, B4FF-156 recovery

was very fast reaching more than 80% in less than 2 min and ~ 90 % after 5 min. These

values are 10% higher than those achieved by the same density flexible foam produced

with PMTAG Polyol. The difference in flexibility between B4FF-156 and PMTAG Polyol

flexible Foam (Table 5.4), as elucidated by the compressive strength and recovery data,

can be related to the differences in OH value and lesser percentage of terminal hydroxyls

190

in their corresponding polyol structure. This indicates the compressive strength and the

flexibility of the flexible foams can be controlled to a relatively large extent by controlling

the OH value and the terminal hydroxyls of the polyol.

Figure 5.11: Recovery (%) in thickness of B4-FF156 (B4-Green Polyol flexible

foam of density 156 kgm-3) versus time.

The properties of the Green Polyol flexible foams also compare favorably with the

commercial and bio based flexible foams. Although the flexible foam industry relies on

petroleum based polyols such as poly ether polyols [9, 49], lipid-based polyol are

increasingly used, particularly as blends such as soy-castor oil-based polyol [50], rapeseed

polyol [51], soy polyol [9, 31], palm oil polyol. [49]

The flexible foams of the present study present compressive strengths that are in the

0.1 MPa to 0.4 MPa range displayed by these foams. The comparison the overall properties

of the flexible foams of the present work with those materials suggest that the Green

Polyols would be very interesting as blend with commercial petroleum polyols and would

provide highly functional flexible foams. One would expect similar or better results than

Time (min)

0 3 6 9 12 1500 3000

Recovery

(

%)

20

40

60

80

100

B4-FF156

191

what was achieved with palm oil polyol for which a 15% substitution with Alfapol, a

petroleum based polyether polyol, enhanced the compressive strength by ~60% [49] or soy

oil polyol where a 30% substitution caused 50% improvement in compressive strength.[9]

The partial replacement commercial petroleum based polyols with the Green Polyols of the

present work in fact show great promise for both flexible and rigid applications.

5.4 Conclusions

Green Polyols with controlled OH value and primary hydroxyls were successfully

synthesized using an alternative, solvent free epoxidation and hydroxylation reactions. The

solvent free pathway has been demonstrated to be able to yield very versatile green polyols

comprised of diols and tetrols terminal groups. The structures of the polyols although

inherited from the feedstock (PMTAG) were dramatically influenced by the reaction

conditions. A complete functionalization of PMTAG has been achieved with moderate

temperature and reaction time conditions. Furthermore, the formic acid moieties that attach

to the polyol backbone under specific reaction conditions can be managed effectively and

even avoided by adequately tuning the time and temperature of epoxidation reaction.

Two designer polyols (so-called B3- and B4-Green Polyols) having OH values of 83

and 119 mg KOH/g, respectively, and 16 and 18% primary hydroxyl, respectively, were

fully characterized and used to produce very functional rigid as well as flexible foam. Note

that a relatively large number of oligomeric material (~45%) was detected in the Green

Polyols.

The thermal transition behavior of the green polyol was dictated by a high-melting and

low-melting portions that are related to the olein-like and stearin –like portion of PMTAG.

192

However, although clearly separated, their associated thermal events were much closer

than in PMTAG or palm oil because of the hydroxyls groups present in the olein-like

portion of the polyol which shifted its crystallization to a higher temperature (~10 °C).

These polyols presented a melting temperature (48 °C) and viscosity profiles that were very

manageable for preparing the rigid and flexible foams.

Both the rigid and flexible foams prepared from the Green Polyols displayed good

thermal stability with onset of decomposition at ~270 °C comparable to other vegetable

oil-based foams. Their closed cell structure as evaluated from SEM images, indicate that

they are suitable for structural and thermal insulation applications. The compressive

strength of the rigid foams prepared from the Green Polyols compare favorably with those

prepared previously from PMTAG via solvent mediation. One can note that there is more

flexibility in the foams made from Green polyol because of the larger range of control of

the structures of the green Polyol compared to the solvent mediated polyol. Interestingly,

the green polyols produced flexible foams with very good flexibility attributes such as very

high recovery (94 %) coupled with a relatively low but tunable compressive strength. The

findings of the present study, particularly the results obtained with the flexible foams, bode

well for the success of the strategy based on a green economical synthetic route for the

production of polyols from vegetable oil based feedstocks.

Acknowledgements: We would like to thank the Grain Farmers of Ontario, Elevance

Renewable Sciences, Trent University, the GPA-EDC, Ontario Ministry of Agriculture,

Food and Rural Affairs, Industry Canada and NSERC for financial support. We also thank

Dr. Michael Floros for his kind help in taking SEM Pictures.

193

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197

6 Conclusion

6.1 General Conclusion

Palm oil is one of the most inexpensive commodity oils in the world, making it a good

candidate feedstock for the synthesis of renewable bio-based polymers, inclusive of

polyurethanes. However, the steric hindrance associated with the dangling chains of the

saturated and mid-chain substituted or unsubstituted unsaturated fatty acids are significant

limitations in the conversion of palm oil into value added materials such as polyols for the

synthesis of polyurethane foams, especially rigid polyurethane foams. This thesis

investigated several chemical and physical strategies to address the dangling chain issues

of palm oil and its subsequent use in the preparation of rigid and flexible PU foams.

Chemical modification of palm oil involved cross metathesis with 1-butene to give a

metathesized palm oil (PMTAG), followed by epoxidation and hydroxylation, and physical

modification involved fractionation of the PMTAG into its highly saturated stearin and

highly unsaturated olein fractions.

6.2 Rigid foams from PMTAG

The structural and compositional analysis of palm oil chemically modified by cross

metathesis with 1-butene (PMTAG) was determined using 1HNMR, GC and HPLC. It was

revealed that metathesis did not affect the saturated moieties of the starting natural oil,

which remained at ~50%, but significantly modified its unsaturated fatty acids. 50% of the

carbon-carbon double bonds of PMTAG were detected at terminal positions, whilst the

remaining fatty acid moieties with internal double bonds were found to have a cis/trans

configuration ratio 2:1. Furthermore, a major part of the unsaturated content in PMTAG

198

was comprised of 9-decenoic acid (D) and 9-dodecenoic acid (Dd), two moieties not

present in the natural oil.

Epoxidation followed by hydroxylation of PMTAG yielded PMTAG polyol, a mixture

of diols, tetrols and hexols with a maximum OH value of 155 mg KOH/g and 24.1 mol%

terminal hydroxyls. The thermal stability and viscosity of PMTAG polyol were in the range

of other vegetable based polyols such as soybean and canola oil polyols, indicating its

suitability as a commodity material for polyurethane foam preparation.

The rigid foams prepared from the PMTAG polyol displayed three (3) times higher

compressive strength compared to the rigid foams of similar density produced from natural

oil polyols such as palm and soybean oil polyols. This indicated that the introduction of the

terminal hydroxyl groups, and correspondingly the removal of the dangling chains at the

carbon-carbon double bonds, resulted in more rigid polyurethane foams compared to those

obtained from the natural oil polyols, corroborating Hypothesis 1. In fact, comparison of

the OH values and compressive strength of the PMTAG polyol with those of the natural

oils reveal that the position of the OH group (i.e., terminal or not) has a more significant

influence on compressive strength compared to OH value alone.

6.3 Flexible foams from PMTAG

Flexible foams with 80 to 90 % recovery were produced from the terminal hydroxyl

PMTAG polyol by excluding the glycerin cross linker and lowering the catalyst

concentration. This supports Hypothesis 2 that flexible foams could be prepared from

PMTAG polyol by alteration in the formulation recipe of the rigid foams, and shows the

suitability of PMTAG polyol for use in flexible foam applications.

199

6.4 Foams from fractionated PMTAG

PMTAG was fractionated using dry and solvent mediated crystallization fractionation.

As expected, the solid fraction (SF) of both methods consisted of the highly saturated

stearin type molecules of PMTAG, which left the liquid fraction (LF) rich in the highly

unsaturated olein type molecules.

The polyols produced from the olein rich fraction (liquid fraction: LF) of the PMTAG

displayed a higher OH value (184 mg KOH/g) compared to PMTAG polyol (155 mg

KOH/g) due to the removal of the saturated components. In fact, the LF-PMTAG polyols

obtained by either fractionation methods possessed the same OH values, indicating

similarity of composition regardless of the fractionation method.

Rigid foams produced from the LF-PMTAG polyols displayed 1.5 times higher

compressive strength than the rigid foam from PMTAG polyol with the same density. This

substantiates that fractionation by dry and solvent crystallization of PMTAG resulted in a

better feed stock, LF-PMTAG, and corresponding polyol for rigid polyurethane foams

application. This supports Hypothesis 3; i.e., that polyols derived from the olein fraction

of PMTAG would make highly rigid foams compared to rigid PMTAG polyol foams.

Flexible foams, prepared from LF-PMTAG polyols using the same formulation

recipe used in case of PMTAG polyol flexible foams, displayed ~ 80% recovery, but lower

compressive strength than analogous foams from flexible PMTAG polyol due to the lower

number of terminal hydroxyls in the former (18- 20 mol %). Thus, the flexible foams

prepared from LF-PMTAG polyols possessed similar recovery but were more flexible than

the PMTAG polyol flexible foams. This validates the suitability of LF-PMTAG polyols

200

for flexible foam applications and corroborates Hypothesis 4 that flexible foams can be

prepared from olein fraction (liquid fraction) of PMTAG by varying the formulation recipe.

6.5 Green Polyols and Foams

Solvent free epoxidation of PMTAG followed by hydroxylation was used to prepare

green PMTAG polyols. Green polyols with variable OH values and no formic acid attached

were obtained by controlling the reaction temperature of the epoxidation reaction (four

batches B1 to B4). The green polyols with lower OH values and terminal hydroxyls (B3-

Green Polyol with OH value 89 mg KOH/g and 16.5 mol% terminal hydroxyls; and B4-

Green Polyol with OH value 119 mg KOH/g and 18.3 mol % terminal hydroxyls) were

used for the preparation of polyurethane foams.

The flexible foams prepared from the Green Polyols (B3 and B4) displayed lower

compressive strength and higher recovery (~94%) than the PMTAG polyol flexible foam

of similar density. In fact, comparison of the OH values, compressive strength and recovery

of similar density foams revealed that compressive strength increased and recovery

decreased with increasing OH value and number of terminal hydroxyl groups. These results

corroborate, therefore, Hypothesis 5, and further shows that both OH value and terminal

hydroxyl groups are important deciding factors of the strength of the foams.

6.6 Summary

To conclude, cross metathesis and fractionation were used singly and in combination

to successfully to reduce the effects of the dangling chains associated the saturated and

unsaturated fatty acids in palm oil. 1-butene cross metathesis of palm oil modified the

unsaturated fatty acids so as to produce terminal double bonded TAGs (PMTAG).

201

Fractionation of PMTAG reduced the proportion of the highly saturated stearin type

molecules in the PMTAG. Terminal hydroxyl polyols produced from PMTAG and

fractionated PMTAG gave polyurethane foams with enhanced rigidity compared to those

produced from natural oils such as soybean oil and palm oil. Furthermore, green polyols

with variable OH value and, therefore, tunable foam compressibility and recovery were

successfully synthesized from PMTAG by solvent free strategy for use in polyurethane

foam preparation.

6.7 Implications of this study

The fundamental understanding obtained from the study indicates that high saturated

fatty acid content in vegetable oils, whilst a significant barrier to oleo-chemical synthesis,

can be mitigated in the case of palm oil by fractionation and cross-metathesis to produce

highly functional polyols. Issues associated with the fatty acid profiles can therefore

generally be addressed using chemical modification, such as cross metathesis, combined

with physical modification, such as fractionation.

6.8 Future Prospects

The present study has investigated the use of cross metathesis, and the fractionation

of the cross metathesized product to rectify the dangling chain issues of natural vegetable

oils which limits their application for rigid foam preparations. However the study has

considered only the cross metathesis of palm oil using 1-butene, which converted only 50%

of total unsaturated fatty acids into terminal double bonds. Instead of 1-butene, ethylene

can be used for cross metathesis in order to convert all unsaturated fatty acids into terminal

202

double bonds and further increase the rigidity of the foams prepared from the cross

metathesized product.

The present study has only used one synthetic technique - epoxidation followed by

hydroxylation - for the polyol synthesis. This strategy was selected since we desired the

maximum OH groups per double bond. In order to establish a more fundamental

understanding on the effect of OH value on the foam properties, however, a detailed study

using different chemical techniques for the polyol synthesis are suggested so as to vary the

number of OH groups per carbon-carbon double bond. Such approaches include

epoxidation followed hydrogenation, or epoxidation followed by hydroformylation.

Another level of improvement for this study can be achieved by varying the formulation

recipe such as catalyst ratio, glycerin content, isocyanate etc. to test their effect(s) on the

foam characteristics in order to design foams for different commercial applications using

optimal amounts of resources. Furthermore, since isocyanate is a dangerous material, use

of non-isocyanate pathways for the foam preparation from PMTAG can be explored, which

will further increase the value of PMTAG.

The effect of cross metathesis on other highly unsaturated vegetable oils such as

soybean oil, canola oil and rapeseed oil for rigid foam applications can also be investigated.

Since there is little high-saturated fatty acid content in these vegetable oils, fractionation

can be avoided, resulting in increased cost savings for the producer.

The scope of the present work was limited to the application of PMTAG into foam

preparations. It has been observed, however, that the SF-Polyol prepared from the solid

fraction of PMTAG has many characteristics similar to commercially available waxes,

203

indicating its suitability for use as commercial waxes. Furthermore, based on the similar

architectures of terminal polyols reported in the literature for the preparation of bio-based

elastomers and plastic sheets, it is anticipated that the PMTAG polyols of this work, too,

may be used in alternative applications such as elastomer and plastic sheets.

204

Appendix

A1 Butene Cross metathesized Palm oil and Polyol Derivatives: Structure

and Physical properties

Table A 1. Table showing the characteristic chemical shift values of PMTAG

Proton Chemical Shift (ppm)

-(CH2)7CH

3 ~0.8-0.9

-(CH2)2CH

3 ~1.0

-(CH2)- 1.4-1.2

-CH2CH

2COO- ~1.6

-CH2CH= 2.1-1.9

-CH2COO- 2.4-2.2

-OCH2CH(O)CH

2O- 4.3-4.1

-CH=CH2 5.0-4.8

-OCH2CH(O)CH

2O- 5.3-5.2

-CH=CH- 5.5-5.3

-CH=CH2 ~5.8

205

Figure A 1: 1H-NMR of Epoxidation of PMTAG in Ethyl Acetate. Terminal double

bond left : >60%

Figure A 2: 1H-NMR of Epoxidation of without solvent. No double bond detected.

Formic ester polyol formed. Terminal double bond left : >60%

206

Figure A 3: 1H-NMR of Epoxidation of with reduced ratio of H2O2 and HCOOH.

Terminal double bond >40% and Internal double bond >5%

Scheme A 1. Possible structure of the formic ester polyol

210

Scheme A 2. Structures of PMTAG Polyol determined by MS and 1H-NMR

211

F1

Time/min

0 1 2 3 4 5

LS

U

0

600

1200

1800

2400F2

Time (min)

6 7 8

LS

U

0

300

600

900

1200

F3

Time (min)9 10 11 12

LS

U

0

100

200

300

400F4

Time (min)

10 12 14 16 18 20

LS

U

0

300

600

900

1200

1500

F5

Time (min)

15 16 17 18 19

LS

U

0

200

400

600F6

Time (min)

18 19 20 21

LS

U

0

100

200

212

Figure A 4. HPLC of PMTAG Polyol Fractions (F1-F8)

F7a

Time (min)

19 20 21 22

LS

U

0

300

600

900

1200F7b

Time (min)

19 20 21 22 23

LS

U

0

40

80

120

160

200

F7c

Time (min)

20 21 22 23

LS

U

0

100

200

300F8

Time (min)

29 30 31 32 33 34 35

LS

U

0

300

600

900

1200

1500

213

A2 Fractionation Strategies for Improving Functional Properties of Polyols

and derived Polyurethane Foams from 1-butene Metathesized Palm Oil

Table A 2. Thermal data of the PMTAG obtained on cooling and heating (at 0.1, 1.0,

5 °C/min). onT , offT and pT , p= 1-6: Onset, offset, and peak temperatures, ,C MH :

Enthalpy, C: crystallization and M: melting.

Cooling Temperature (C) (J/g)

°C/min onT 1T 2T 3T 4T 5T 6T offT 1H 2H CH

0.1 31.7 30.5 11.8 -11.2 -23.0 -30.0 28.8 157.

3 186.1

1.0 26.9 25.5 9.4 4.9 0.4 -14.2 -

21.0 -47.2 26.9 74.3 101.2

5.0 24.4 22.9 4.1 -6.4 -22.7 -31.7 -

43.6 -54.1 24.4 67.8 92.1

Table A 3. Fractionation of PMTAG by crystallization. OnT : onset of crystallization

Experiment OnT

(°C) aF1 14.5 aF2 13.5 aF3 10.0 aF4 8.5 bF5 11.5

a: Dry Fractions

b: Solvent Fractions

214

Figure A 5: Crystallization thermograms of (a) LF(D)-PMTAG , (b)SF(D)-PMTAG

obtained at 5 °C/min and heating profiles of (c) LF(D)-PMTAG , (d) SF(D)-PMTAG at 5

°C/min..

(a) Liquid Fractions

Temperature /oC

-10 0 10 20 30

He

at

Flo

w

/W

g-1

(

Exo

up

) PMTAG

LF1

LF2

LF3

LF4

4 o

C

24.4

14.5

13.5

10.0

8.5

TO

n (

oC

)

0.5

(b) Solid Fractions

Temperature /oC

-10 0 10 20 30

Heat

Flo

w

/W

g-1

(

Exo u

p)

PMTAG

SF1

SF2

24.4

20.5

24.3

24.8

4 o

C

SF3

22.5SF4

TO

n (

oC

)

0.5

(c) Liquid Fractions

Temperature /oC

-20 0 20 40

He

at

Flo

w

/W

g-1

(

En

do

do

wn

)

PMTAG

LF1

LF2

LF3

LF4

(d) Solid Fractions

Temperature /oC

-20 0 20 40

Heat

Flo

w

/W

g-1

(

Endo d

ow

n)

-1.0

-0.5

0.0

0.5

PMTAG

SF1

SF2

SF3

SF4

215

(a)

Temperature /oC

-30 -20 -10 0 10 20 30 40

He

at F

low

/W

g-1

(E

xo u

p)

0.0

0.2

0.4

0.6

0.8

PMTAG

LF(S)

Ton (

oC

)

24.4

11.45

Figure A 6: Crystallization thermograms of (a) LF(S)-PMTAG , (b)SF(S)-PMTAG

obtained at 5 °C/min and heating profiles of (c) LF(S)-PMTAG , (d) SF(S)-PMTAG at 5

°C/min.

(b)

Temperature /oC

-30 -20 -10 0 10 20 30 40

Heat

Flo

w

/W

g-1

(Exo u

p)

0.0

0.2

0.4

0.6

0.8

1.0

1.3

1.5

SF(S)

PMTAG24.4

29.1

Ton (

oC

)

(c)

Temperature /oC

-30 -15 0 15 30 45 60

Heat

Flo

w

/W

g-1

(Endo d

ow

n)

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

PMTAG

LF(S)

(d)

Temperature /oC

-30 -15 0 15 30 45 60

Heat

Flo

w

/W

g-1

(Endo d

ow

n)

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

PMTAG

SF(S)

216

Table A 4. Thermal data of SF- and LF-PMTAG. onT , offT , 1 3T : onset, offset and

peak temperatures (C), SH , OH , and H (J/g): Enthalpy of the stearin and olein

portions, and total enthalpy, respectively.

Cooling cycle (5 C/min)

Exotherms Enthalpy (J/g)

T (C) onT offT 1T 2T 3T SH OH H

SF- PMTAG 24.9 -31.5 23.9 4.2 -21.3 26.0 64.0 90.0

LF-PMTAG 14.3 -31.5 13.3 4.9 -21.7 9.0 61 70

Heating cycle (5 C/min)

T (C) Endotherms Exotherms

onT offT 1T 2T 3T 4T 5T 1RT 2RT

SF-PMTAG -25.3 49.3 46.6 25.6 13.3 -4.6 -17.2 18.0 2.3

H (J/g) -- -- 28.4 92.7 20.7 10.9 4.9 2.5

LF-PMTAG -25.6 34.5 31.6 25.6 15.4 -4.4 -17.3 18.7 3.1

H (J/g) shoulder 37.9 33.6 9.0 0.4 2.4

.

217

Figure A7. 1H-NMR spectra of SF-PMTAG

218

Figure A 8. 1H-NMR spectra of LF-PMTAG

219

Table A 5. 1H-NMR chemical shifts of SF-PMTAG and LF- PMTAG

Fractionated

PMTAG

1H-NMR Chemical shifts (500 MHz), δ, in CDCl3 (ppm)

LF(D)-

PMTAG

5.8 (m, 0.8H), 5.3-5.6 (m, 1.8H), 5.2 (m, 1H) ,5.0-4.8 (dd, 1.3H) ,4.4-

4.2 (dd, 2.0H), 4.2-4.0 (dd, 2.0H), 2.4-2.2 (dd, 6.0H), 1.6-1.2 (m, 58H), 1.2-

1.0 (t, 1.1H), 1-0.8 (t, 5.3H)

LF(S)-

PMTAG

5.8 (m, 0.5H), 5.3-5.6 (m, 2.2H), 5.2 (m, 1.0H) ,5.0-4.8 (dd, 1.1H)

,4.4-4.2 (dd, 2.0H), 4.2-4.0 (dd, 2.0H), 2.4-2.2 (dd, 6.2H), 1.6-1.2 (m, 63H),

1.2-1.0 (t, 1.4H), 1-0.8 (t.5.8H)

SF(D)-

PMTAG

5.8 (m, 0.7H), 5.3-5.6 (m, 1.6H), 5.2 (m, 1.0H) ,5.0-4.8 (dd, 1.2H)

,4.4-4.2 (dd, 2.0H), 4.2-4.0 (dd, 2.0H), 2.4-2.2 (dd, 6.2H), 1.6-1.2 (m, 62H),

1.2-1.0 (t, 1.1H), 1-0.8 (t.5.6H)

SF(S)-

PMTAG

5.8 (m, 0.4H), 5.3-5.6 (m, 1.7H), 5.2 (m, 1.0H) ,5.0-4.8 (dd, 0.81H)

,4.4-4.2 (dd, 2.0H), 4.2-4.0 (dd, 2.0H), 2.4-2.2 (dd, 6.2H), 1.6-1.2 (m, 68H),

1.2-1.0 (t,0 9H), 1-0.8 (t.6.3H)

220

Figure A 9. 1H-NMR spectra of LF-Polyol

221

Figure A 10. 1H-NMR spectra of SF-Polyol

Table A 6: Chemical shifts (δ) and their integration values from 1HNMR.

Polyols 1H-NMR Chemical shifts, δ, in CDCl3 (ppm)

LF- Polyol 5.2 (m, 1H), 4.4-4.2 (dd, 2H), 4.2-4.0 (dd, 2H), 3.8 -3.2 (m, 4.5H),

2.4-2.2 (dd, 6.6H), 1.6-1.2 (m, 68H), 1.2-1.0 (t, 1.12H), 1-0.8 (t.5.6H)

SF- Polyol 5.2 (m, 1H), 4.4-4.2 (dd, 2H), 4.2-4.0 (dd, 2H), 3.8 -3.2 (m, 4.14H),

2.4-2.2 (dd, 7.2H), 1.6-1.2 (m, 70H), 1.2-1.0 (t, 1.63H), 1-0.8 (t.7.8H)

Table A 7. Temperature of degradation at 1, 5 and 10% weight loss (1%

dT ,5%

dT , 10%

dT

, respectively), DTG peak temperatures ( DT ), and extrapolated onset ( onT ) and offset (

offT ) temperatures of degradation of LF- and SF- Polyols

Temperature (C) Weight loss (%) at

1%

dT 5%

dT 10%

dT onT 1DT DT offT

onT 1DT DT

LF-Polyol 194 291 315 328 228 376 469 15 2 58

SF-Polyol 177 261 304 294 237 389 422 8 4 67

223

Table A 8. Thermal data of LF- and SF-Polyols obtained on cooling and heating

(both at 5 °C/min). Onset ( onT ), offset (offT ), and peak temperatures ( 1 3T ), Enthalpy of

crystallization ( CH ), and Enthalpy of melting ( MH ). aShoulder peak

SF-Polyol Temperature (C) Enthalpy (J/g)

onT 1T 1 'T 2T 3T offT CH

Cooling 32.1 31.6 28.3 20.1 13.4 -1.2 113

offT 1T 2T 3T 4T onT MH

Heating 49.8 47.2 36.7 25.6a 23.8 2.8 101

LF-Polyol Temperature (C) Enthalpy (J/g)

onT 1T 2T 3T offT CH

Cooling 28.9 25.8 21.3 1.5 0.8 99.6

onT 1T a 2T 3T 4T a offT

MH

Heating 6.6 41.6 32.5 27.2 20.9 44.8 89.9

Table A 9. Temperature of degradation at 1, 5 and 10% weight loss ( 1%

dT , 5%

dT , 10%

dT

, respectively), DTG peak temperatures ( DT ), and extrapolated onset ( onT ) and offset ( offT

) temperatures of degradation of LF(D)-Polyol Foams

Temperature (C) Weight loss (%)

at

5%

dT 10%

dT onT 1DT 2DT 3DT offT onT 1DT 2DT 3DT

LF-Polyol Rigid

Foam(RF163) 265 285 251 302 361 462 494 3 18 45 67

5%

dT 10%

dT onT 1DT 2DT 3DT offT onT 1DT 2DT 3DT

LF-Polyol

Flexible Foam

(FF161)

249 278 250 307 362 450 486 5 17 44 68

224

A3 Solvent Free Synthesis of Polyols from 1-Butene Metathesized Palm Oil

for Use of Polyurethane Foams

Table A 10: Properties of diphenylmethane diisocyanate (MDI)

Appearance Dark brown liquid

Composition Polymeric MDI: 40-50%

(4, 4’ Diphenylmethane Diisocyanate):30-

40%

MDI mixed isomers: 15-25%

Boiling Point (°C) 208

NCO (wt%) 31.5

Functionality 2.4

Equivalent weight (g/mol) 133

Viscosity @ 25 °C (mPa·s) 200

Bulk density (Kgm-3) 1234

Table A 11. 1H-NMR chemical shifts, δ, of B1-, B2-, B3- and B4-epoxy PMTAG.


B1-epoxy PMTAG 8.2 (m, 0.28H), 5.8 (m, 0.2H) 5.2 (m, 0.92H) ,5.0-4.8 (dd, 0.40H) ,4.4-4.2

(dd, 2H), 4.2-4.0 (dd, 2H), 2.85 (m, 0.54H), 2.7-2.4 (m, 1.5H) 2.4-2.2 (dd,

7.2H), 1.8-1.2 (m, 74H), 1.2-1.0 (t, 1.3H), 1-0.8 (t, 6.6H)

B2-epoxy PMTAG 8.2 (m, 0.28H), 5.8 (m, 0.18H) 5.2 (m, 1H) ,5.0-4.8 (dd, 0.42H) ,4.4-4.2

(dd, 2H), 4.2-4.0 (dd, 2H), 2.85 (m, 0.48H), 2.7-2.4 (m, 1.4H) 2.4-2.2 (dd,

6.6H), 1.6-1.2 (m, 70H), 1.2-1.0 (t, 1.3H), 1-0.8 (t.7.2H)

B3-epoxy PMTAG 5.8 (m, 0.34H), 5.2 (m, 1H) ,5.0-4.8 (dd, 0.52H) ,4.4-4.2 (dd, 2H), 4.2-4.0

(dd, 2H), 2.85 (m, 0.50H), 2.7-2.4 (m, 1.9H), 2.4-2.2 (dd, 6.2H), 1.6-1.2

(m, 68H), 1.2-1.0 (t, 1.6H), 1-0.8 (t.6.4H)

B4-epoxy PMTAG 5.8 (m, 0.26H), 5.2 (m, 1.1H) ,5.0-4.8 (dd, 0.42H) ,4.4-4.2 (dd, 2H), 4.2-

4.0 (dd, 2H), 2.85 (m, 0.57H), 2.7-2.4 (m, 1.4H), 2.4-2.2 (dd, 6.5H), 1.6-

1.2 (m, 70H), 1.2-1.0 (t, 1.7H), 1-0.8 (t, 5.8H)

225

Table A 12. 1H-NMR chemical shifts, δ, of B1-, B2-, B3- and B4-PMTAG Green

Polyols


B1-Green Polyol 8.2 (m, 0.28H) 5.2 (m, 1H) ,5.0-4.8 (dd, 0.40H) ,4.4-4.2 (dd, 2H), 4.2-4.0

(dd, 2H), 3.8 -3.2 (m, 2.1H), 2.4-2.2 (dd, 6.6H), 1.6-1.2 (m, 69H), 1.2-1.0

(t, 1.3H), 1-0.8 (t, 6.6H)

B2-Green Polyol 8.2 (m, 0.28H) 5.2 (m, 1H) ,5.0-4.8 (dd, 0.42H) ,4.4-4.2 (dd, 2H), 4.2-4.0

(dd, 2H), 3.8 -3.2 (m, 2.2H), 2.4-2.2 (dd, 7.4H), 1.6-1.2 (m, 76H), 1.2-1.0

(t, 1.3H), 1-0.8 (t.7H)

B3-Green Polyol 5.2 (m, 1H) ,5.0-4.8 (dd, 0.52H) ,4.4-4.2 (dd, 2H), 4.2-4.0 (dd, 2H), 3.8 -

3.2 (m, 2.2H), 2.4-2.2 (dd, 6.8H), 1.6-1.2 (m, 58H), 1.2-1.0 (t, 1.6H), 1-0.8

(t.5.8H)

B4-Green Polyol 5.2 (m, 1H) ,5.0-4.8 (dd, 0.44H) ,4.4-4.2 (dd, 2H), 4.2-4.0 (dd, 2H), 3.8 -

3.2 (m, 1.6H), 2.4-2.2 (dd, 4.2H), 1.6-1.2 (m, 45H), 1.2-1.0 (t, 1.7H), 1-0.8

(t, 5.8H)

226

Figure A 11: 1HNMR of Selected Polyols

Figure A11a. 1HNMR of B1-Green Polyol.

227

Figure A11b. 1HNMR of B2-Green Polyol.

228

Figure A11c. 1HNMR of B3-Green Polyol

229

Figure A11d. 1HNMR of B4-Green Polyol

230

Figure A 12. GPC chromatogram of B3-Green Polyol (B3), B4-Green Polyol (B4)

and standard PMTAG polyol (S).

Table A 13. Area% of peaks P1 and P2 from GPC

Polyols Peaks Area % Oligomers

B3-Green Polyol P1 45 45%

P2 54

B4-Green Polyol P1 37 37%

P2 63

PMTAG Polyol P1 13 13%

P2 87

P1: Mn: 4437 g/mol and Mw: 7030 g/mol

P2: Mn: 721 g/mol, and Mw: 1463 g/mol

Time (min)

18 19 20 21 22

Inte

nsity(m

V)

0

1

2

3

4B3

B4

S

P1

P2

231

Table A 14. Column chromatography, HPLC and 1H NMR data of the fractions of

B4-Polyol. EA: Hx: ratio of ethyl acetate and hexanes, the solvents used for column

chromatography. RT: HPLC Retention time (min); FA1: Fatty acids with terminal double

bond (9-decenoic acid), FA2: Fatty acid with internal double bond (9-dodecenoic acid);

FA3: Fatty acid with internal double bond (oleic acid). The structure FA1, FA2 and FA3 are

presented in Scheme A3.

Fraction EA: Hx RT A

%

1H-NMRchemical shift Potential structures

F1 1:10 5-9

73

5.8 (m, 0.28H), 5.2 (m, 1H), 4.8-

5.0 (dd, 0.56), 4.3 (dd, 2H), 4.1

(dd, 2H), 2.4 (t, 6H), 2.0 (m, 1H),

1.6 (m), 1.4-1.2 (m), 1.0 (t,

0.8H), 0.8 (t, 7H)

TAG structure

No polyols

Contains FA1, FA2, and

FA3

F2 1:10 7.25

1

4.2-4 (m,0.47H), 2.3 (m, 0.46 H),

1.4-1.2 (m), 1.6(m), 0.8 (m, 1H)

Not a TAG structure

Hydroxylated products

containing FA3

F3 1:10 7.2-11 5.8 (m), 5.2 (m) 4.8(m) 4.4-4.0

(m), 2.4 (m), 2.0 (m), 1.6 (m),

1.4-1.2 (m), 0.8 (t)

Not a TAG structure.

Hydroxylated products,

containing FA3 and FA1;

No FA2

F4 1:8 10.2

1

5.8 (m, 0.20H), 5.2 (m, 1H), 5.0

(dd, 0.4), 4.3 (dd, 2H), 4.1 (dd,

2H), 3.6-3.2 (m, 2H) 2.4 (t, 6H),

2.0 (m, 1H), 1.6 (m), 1.4-1.2 (m),

1.0 (t, 1.8H), 0.8 (t, 4.5H)

TAG structure,

Diols with FA2 and FA3

Contains FA1

F5 1:8 15.2-

16.1 5

5.2 (m, 1H), 4.3 (dd, 2H), 4.1

(dd, 2H), 3.6-3.2 (m) 2.4(t, 6H),

1.6 (m), 1.4-1.2 (m), 0.8 (t, 9H)

Diols, including diol from

FA3

No FA1 and FA2

F6 1:6 16.2-

22.2

12

5.8 (m, 0.20H), 5.2 (m, 1H), 4.8-

5.0 (dd, 0.4), 4.3 (dd, 2H), 4.1

(dd, 2H), 3.6-3.2 (m,) 2.4 (t, 6H),

2.0 (m), 1.6 (m), 1.4-1.2 (m), 1.0

(t, 0.8H), 0.8 (t, 6.6H)

Diols From FA1, FA2 and

FA3.

Contains FA1

F7 1:6 30.1-

34.1

8

5.8 (m, 0.2H), 5.2 (m, 1H), 4.8-

5.0 (dd, 0.4H), 4.3 (dd, 2H), 4.1

(dd, 2H), 3.6-3.2 (m, 3.4H) 2.4 (t,

6H), 1.6 (m), 1.4-1.2 (m), 1.0 (t,

1.6H), 0.8(t, 4H)

Tetrols

232

Scheme A3. Fatty acid (FA1, FA2 and FA3) structures from the B4-Polyol.

Table A15. Thermal data of Green PMTAG Polyols obtained on cooling and heating

(both at 5 °C/min). Onset ( onT ), offset ( offT ), and peak temperatures ( 1 3T ), enthalpy of

crystallization ( CH ), and enthalpy of melting ( MH ). aShoulder peak

Cooling Temperature (C) Enthalpy

(J/g)

onT 1T 2T 3T 4T offT CH

B3-Green Polyol 26.8 24.7 17.3 11.5 -- -4.3 73.6

B4-Green Polyol 28.6 26.0 12.1 -- -- -4.7 84.1

Heating Temperature (C) Enthalpy

(J/g)

onT 1T a 2T 3T 4T offT MH

B3-Green Polyol -1.2 43.9 32.5 24.4 20.9 48.3 91.9

B4-Green Polyol 1.5 43.4 32.3 22.4 -- 49.5 91.6

FA3: oleic acid

FA2: 9-dodecenoic acid

FA1: 9-decenoic acid

synthesis of lipid based polyols from 1-butene ...343... · oil for use in polyurethane foam...

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