UNIVERSITI PUTRA MALAYSIA

SYNTHESIS AND CHARACTERIZATION OF SAGO STARCH ESTERS AND THEIR BLENDS WITH

POLY(VINYL CHLORIDE)

SEE YAW KOON

FS 2007 29

SYNTHESIS AND CHARACTERIZATION OF SAGO

STARCH ESTERS AND THEIR BLENDS WITH

POLY(VINYL CHLORIDE)

SEE YAW KOON

MASTER OF SCIENCE

UNIVERSITI PUTRA MALAYSIA

2007

SYNTHESIS AND CHARACTERIZATION OF SAGO

STARCH ESTERS AND THEIR BLENDS WITH

POLY(VINYL CHLORIDE)

By

SEE YAW KOON

Thesis Submitted to the School of Graduate Studies, Universiti Putra

Malaysia, in Fulfilment of the Requirements for the Degree of

Master of Science

February 2007

To my beloved parent, wife and daughter, for their support

and patience with this thesis.

To my sister and brother in law;

to my niece and bother, and to all the others.

See Y. K.

Abstract of thesis presented to the Senate of Universiti Putra Malaysia in

fulfilment of the requirement for the degree of Master of Science

SYNTHESIS AND CHARACTERIZATION OF SAGO STARCH ESTERS

AND THEIR BLENDS WITH POLY(VINYL CHLORIDE)

By

SEE YAW KOON

February 2007

Chairman: Professor Dzulkefly Kuang Abdullah, PhD

Faculty: Science

Esterifying of palm oil based oleochemicals like hexanoyl, octanoyl and lauroyl

chloride onto dried sago starch by using formic acid as an initiator had been

studied in the absence of an organic solvent. A stream of nitrogen gas had been

used to eliminate the hydrochloric acid produced by the reaction. The optimum

conditions in esterifying of starch hexanoate, starch octanoate and starch lauroate

had been studied based on the highest percentage of the recuperation yield.

About 89% of starch hexanoate, 86% of starch octanoate and 80% of starch

lauraote were obtained under optimized conditions with the degree of

substitution (DS) of 1.3, 1.2 and 1.2 respectively. Esterification was evidenced

by the presence of ester carbonyl peak in Fourier transform infrared (FT-IR) and

1H nuclear magnetic resonance (

1H-NMR). The ester group was found to act like

an internal plasticizer because of the reduction of hydrogen bonds between the

starch molecules. The DS of starch esters was determined by elemental analysis.

The TGA had shown that the prepared starch esters had higher thermal stability

than native starch and increased with the increasing of side-chain length and DS.

The DSC thermograms of esterified sago starch showed the depression of glass

transition temperature (Tg) from shorter side-chain length starch ester (starch

hexanoate, 85 oC) to longer side-chain length starch ester (starch lauroate, 36

oC).The mechanical properties of starch esters were determined. Starch lauroate

with the longest side chain length had measurable tensile strength (11.6 ± 0.5

MPa) and elongation at break (2.4 ± 0.3 %) properties compared to starch

hexanoate, starch octanoate and native starch. Tensile strength and elongation at

break depended on the side-chain length and the DS.

Starch hexanoate, starch octanoate and starch lauroate were blended with

poly(vinly chloride) (PVC) at various proportions by using conventional solvent-

casting technique. The FT-IR analysis showed that there were no intermolecular

interactions between starch esters and PVC in room temperature. Thermal and

mechanical properties, water absorption and biodegradation were investigated as

a function of blend composition. The existence of starch esters had enhanced the

thermal properties of PVC and increased with the increasing of starch ester

content. For all blends, the mechanical properties (tensile strength and elongation

at break) retained satisfactory up to 20 wt % for starch ester content. The higher

the content of starch esters was the greater the decreased of mechanical

properties. The blends had shown a minimal water uptake (< 4 wt %) even at the

highest starch ester content (70%). The extent of their biodegradability, after

exposure to sludge, was assessed by weight loss measurements. It was found that

the blends were biodegradable, and the biodegradation rate decreased with

increasing DS.

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi keperluan untuk ijazah Master Sains

SINTESIS DAN PENCIRIAN ESTER KANJI SAGU DAN

CAMPURANNYA DENGAN POLI(VINIL KLORIDA)

Oleh

SEE YAW KOON

Februari 2007

Pengerusi: Profesor Dzulkefly Kuang Abdullah, PhD

Fakulti: Sains

Mengester oleokimia asas minyak sawit seperti heksanoil, octanoil dan lauroil

klorida keatas kanji sagu yang kering dengan menggunakan asid formik sebagai

pemula telah dikaji dalam ketidakhadiran sebarang larutan organik. Satu aliran

gas nitrogen telah diguna untuk menyingkir asid hidroklorik yang terhasil oleh

tindak balas. Keadaan-keadaan optimum dalam mengester kanji heksanoat, kanji

oktanoat dan kanji lauroat telah dikaji berdasarkan kepada peratusan hasil

pemulihan yang tertinggi. Kira-kira 89% kanji heksanoat, 86% kanji octanoat

and 80% kanji lauroat telah diperolehi di bawah keadaan-keadaan teroptimum

dengan darjah penggantian (DS) 1.3, 1.2 and 1.2 masing-masing. Pengesteran

telah terbukti oleh kehadiran puncak karbonil ester dalam inframerah Fourier

Transform (FT-IR) dan 1H resonan magnetik nuklear (

1H-NMR). Kumpulan

ester telah dijumpai bertindak selaku bahan plastik dalaman sebab ia

mengurangkan ikatan hidrogen antara molekul kanji. DS ester kanji telah

ditentukan dengan analisis pengunsuran. TGA telah menunjukkan bahawa ester-

ester kanji yang tersedia mempunyai kestabilan terma yang lebih tinggi daripada

kanji semula jadi dan meningkat dengan peningkatan kepanjangan rantai sisi dan

DS. Termogram DSC bagi kanji sagu yang terester menunjuk penurunan suhu

peralihan kaca (Tg) dari ester kanji yang lebih pendek rantai sisi (kanji heksanoat,

85 oC) kepada ester kanji yang lebih pangjang rantai sisi (kanji lauroat, 36

oC) .

Sifat-sifat mekanikal ester-ester kanji telah ditentu. Kanji lauroat dengan

kepanjangan rantai sisi yang terpanjang mempunyai sifat-sifat kekuatan tegangan

(11.6 ± 0.5 %) dan perpanjangan pada putus (2.4 ± 0.3 %) yang boleh diukur

berbanding dengan kanji hexanoat, kanji octanoat dan kanji asal. Kekuatan

tegangan dan perpanjangan pada putus bergantung kepada kepanjangan rantai

sisi dan DS.

Kanji heksanoat, kanji oktanoat dan kanji lauroat telah dicampur dengan

poli(vinil klorida) (PVC) pada pelbagai nisbah dengan menggunakan teknik

pembalutan larutan yang biasa. Analysis FT-IR menunjukkan bahawa tiada

interaksi antara molekul di antara ester kanji dan PVC dalam suhu bilik. Sifat-

sifat terma dan mekanikal, penyerapan air, dan biodegradasi telah dikaji sebagai

fungsi komposisi campuran. Kehadiran ester kanji telah menambah sifat-sifat

terma PVC dan meningkat dengan peningkatan kandungan ester kanji. Bagi

semua campuran, sifat-sifat mekanikal (kekuatan tegangan dan perpanjangan

pada putus) adalah kekal sehingga 20 wt % kandungan ester kanji. Semakin

tinggi kandungan ester-ester kanji, semakin kurang sifat-sifat mekanikalnya.

Campuran-campuran telah menunjukkan pengambilan air yang minimal (< 4 wt

%) walaupun pada kandungan ester kanji yang tertinggi (70%). Takat

kebolehdegradasinya, selepas dedahkan kepada lumpur, telah dinilai dengan

pengukuran kehilangan berat. Adalah didapati bahawa campuran-campuran

adalah boleh dibiodegradasi, dan kadar biodegradasi berkurangan dengan

peningkatan DS.

ACKNOWLEDGEMENTS

First and foremost, I would like to express my deepest gratitude and appreciation

to my supervisor, Professor Dr. Dzulkefly Kuang Abdullah and members of the

supervisory committee, Professor Dr. Anuar Kassim and Associate Professor Dr.

Abdul Halim Abdullah for their advices, caring, guidance and patience

supervision throughout the duration of the study.

I owe my parent, wife and daughter much gratitude for their love and support.

These are the strength that cheers me up throughout this study. I would like to

take this opportunity to express my deepest appreciation to the staffs of the

Chemistry Department of UPM, Kak. Rus, En. Ismail, En. Zainal, En. Kamal,

Kak. Dina and En. Abas for their co-operation and help during the study.

I would like to give a huge thank you to my friends Chee Siong, Azizul, Sooi

Kim and Azri, for they are always standing by to offer their constructive

comments and sharing their knowledge with me. To my housemates Kevin, Chee

Cherng, Yin Seng, Chiang Seng and Chong Boon for all the moral support.

I would like to acknowledge the Ministry of Science, Technology and Innovation

of Malaysia for funding this research through IRPA research grant. Thanks to all

whom might have neglected their names that helped to make this study possible.

I certify that an Examination Committee has met on 13rd

February 2007 to

conduct the final examination of See Yaw Koon on his Master of Science thesis

entitled “Synthesis and Characterization of Sago Starch Esters and Their Blends

with Poly(Vinyl Chloride)” in accordance with Universiti Pertanian Malaysia

(Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree)

Regulations 1981. The Committee recommends that the candidate be awarded

the relevant degree. Members of the Examination Committee are as follows:

Md. Jelas Haron, PhD

Professor

Faculty of Science

Universiti Putra Malaysia

(Chairman)

Mohd Zaizi Desa, PhD

Associate Professor

Faculty of Science

Universiti Putra Malaysia

(Internal Examiner)

Mohamad Zaki Ab. Rahman, PhD

Associate Professor

Faculty of Science

Universiti Putra Malaysia

(Internal Examiner)

Hamdan bin Suhaimi, PhD

Professor

Faculty of Science and Technology

Universiti Malaysia Terengganu

(External Examiner)

______________________________

HASANAH MOHD GHAZALI, PhD

Professor/Deputy Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

This thesis submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfilment of the requirement for the degree of Master of Science.

The members of the Supervisory Committee are as follows:

Dzulkefly Kuang bin Abdullah, PhD

Professor

Faculty of Science

Universiti Putra Malaysia

(Chairman)

Anuar bin Kassim, PhD

Professor

Faculty of Science

Universiti Putra Malaysia

(Member)

Abdul Halim bin Abdullah, PhD

Associate Professor

Faculty of Science

Universiti Putra Malaysia

(Member)

______________________

AINI IDERIS, PhD

Professor/Dean

School of Graduate Studies

Universiti Putra Malaysia

Date: 14 JUNE 2007

DECLARATION

I hereby declare that the thesis is based on my original work except for

quotations and citations which have been duly acknowledged. I also declare that

it has not been previously or concurrently submitted for any other degree at UPM

or other institutions.

________________

SEE YAW KOON

Date: 31 August 2007

TABLE OF CONTENTS

Page

DEDICATION ii

ABSTRACT iii

ABSTRAK v

ACKNOWLEDGEMENTS viii

APPROVAL ix

DECLARATION xi

LIST OF TABLES xv

LIST OF FIGURES xvii

LIST OF ABBREVIATIONS xx

CHAPTER

1 INTRODUCTION

1.1 General Review 1

1.2 Justification of the Study 2

1.3 Objectives of the Study 4

2 LITERATURE REVIEW

2.1 Starch 5

2.1.1 Molecular Structure 5

2.1.2 Starch Granule and Its Properties 8

2.1.3 Applications and Importance of Starch 9

2.2 Sago Palm (Metroxylon spp.) 11

2.3 Sago Starch 13

2.3.1 Molecular Structure and Starch Granule 14

2.3.2 Properties of the Sago Starch 15

2.3.3 Utilization of Sago Starch in Malaysia 15

2.4 Plastics 17

2.4.1 Classification of Plastics 19

2.4.2 Properties of Plastics 20

2.5 Poly(vinyl Chloride) (PVC) 26

2.5.1 Production of PVC 27

2.5.2 Properties and Its Uses 28

2.6 Oleochemicals 31

2.6.1 Palm Oil Based Oleochemicals 32

2.7 Modification of Starch 35

2.7.1 Starch Chemical Modification –

Esterification

37

2.8 Biodegradation 40

2.9 Starch – Polymer Blends 42

2.10 Suitability of Sago Starch to Produce Starch Esters

and Plastic Materia

44

2.10.1 Quality 44

2.10.2 Particle Size 45

2.10.3 Thermal Stability 46

3 METHODOLOGY

3.1 Materials 47

3.2 Synthesis of Starch Esters 47

3.2.1 Optimization of Esterification 49

3.2.2 Determination of the Degree of Substitution

(DS)

49

3.2.3 Analysis of the Starch Esters by FT-IR

Spectroscopy

50

3.2.4 Analysis of the Starch Esters by 1H NMR

Spectroscopy

50

3.2.5 Thermal Analysis of the Starch Esters 50

3.2.6 Mechanical Properties of the Starch Esters 51

3.3 Preparation of Starch Esters/Poly(vinyl chloride)

Blend Films

52

3.3.1 Thickness Measurements 53

3.3.2 Analysis of Starch Esters/PVC Blends by

FT-IR Spectroscopy

53

3.3.3 Thermal Analysis of Starch Esters/PVC

Blends

53

3.3.4 Mechanical Properties of Starch Esters/

PVC Blends

54

3.3.5 Water Absorption of Starch Esters/PVC

Blends

54

3.3.6 Biodegradation of Starch Esters/PVC

Blends

55

4 RESULTS AND DISCUSSION

4.1 Esterification 56

4.1.1 Optimization of Esterification 58

4.1.2 Determination of Degree of Substitution

(DS) of Starch Esters

66

4.1.3 FT-IR Analysis of Starch Esters 68

4.1.4 1H NMR Analysis of Starch Esters 70

4.1.5 Thermal Properties Analysis of Starch

Esters

73

4.1.6 Mechanical Properties of the Starch Esters 78

4.2 Starch Esters/Poly(vinyl chloride) Blend Films 79

4.2.1 FT-IR Analysis of Blends 81

4.2.2 Thermal Analysis of Blends 83

4.2.3 Mechanical Properties of Blends 90

4.2.4 Water Absorption of Starch Esters/ PVC

Blends

94

4.2.5 Biodegradation of Starch Esters/PVC

Blends

98

5 CONCLUSION

5.1 Conclusion 102

5.2 Recommendation for Further Studies 104

REFERENCES 107

APPENDICES 114

BIODATA OF THE AUTHOR 119

LIST OF TABLES

Table Page

2.1 Ratio between amylose and amylopectin of different starches 8

2.2 Representative properties of commercial grade of PVC 29

2.3 Comparison the production of palm oil based oleochemicals

between Malaysia and world

34

2.4 Fatty acid chlorides and its properties 36

2.5 Modification of starch 38

4.1(a) Influence of concentration of formic acid (FA) on the

recuperation yield (RY) and DS of starch hexanoate (6

eq/glucose of hexanoyl chloride, 40 minutes of reaction time

and 90 oC of reaction temperature)

59

4.1(b) Influence of concentration of formic acid (FA) on the

recuperation yield (RY) and DS of starch octanoate (3

eq/glucose of octanoyl chloride, 40 minutes of reaction time

and 90 oC of reaction temperature)

59

4.1(c) Influence of concentration of formic acid (FA) on the

recuperation yield (RY) and DS of starch lauroate (3.4

eq/glucose of lauroyl chloride, 40 minutes of reaction time and

90 oC of reaction temperature)

59

4.2(a) Influence of the concentration of hexanoyl chloride (HC) on

the recuperation yield (RY) and DS of starch hexanoate (4.3

eq/glucose of formic acid, 40 minutes of reaction time and 90 oC of reaction temperature)

62

4.2(b) Influence of the concentration of octanoyl chloride (OC) on

the recuperation yield (RY) and DS of starch octanoate (4.3

eq/glucose of formic acid, 40 minutes of reaction time and 90 oC of reaction temperature)

62

4.2(c) Influence of the concentration of lauroyl chloride (LC) on the

recuperation yield (RY) and DS of starch lauroate (4.3

eq/glucose of formic acid, 40 minutes of reaction time and 90 oC of reaction temperature)

62

4.3(a) Influence of the duration of the reaction on the recuperation

yield (RY) and DS of starch hexanoate (4.3 eq/glucose formic

acid, 6.0 eq/glucose of hexanoyl chloride and 90 oC of reaction

temperature)

64

4.3(b) Influence of the duration of the reaction on the recuperation

yield (RY) and DS of starch octanoate (4.3 eq/glucose formic

acid, 3.8 eq/glucose of octanoyl chloride and 90 oC of reaction

temperature)

64

4.3(c) Influence of the duration of the reaction on the recuperation

yield (RY) and DS of starch lauroate (4.3 eq/glucose of formic

acid, 4.0 eq/glucose of lauroyl chloride and 90 oC of reaction

temperature)

64

4.4(a) Influence of the temperature (T) on the recuperation yield

(RY) and DS of starch hexanoate (4.3 eq/glucose formic acid,

6.0 eq/glucose of hexanoyl chloride and 40 minutes of reaction

time)

65

4.4(b) Influence of the temperature (T) on the recuperation yield

(RY) and DS of starch octanoate (4.3 eq/glucose formic acid,

3.8 eq/glucose of octanoyl chloride and 40 minutes of reaction

time)

65

4.4(c) Influence of the temperature (T) on the recuperation yield

(RY) and DS of starch lauroate (4.3 eq/glucose of formic acid,

4.0 eq/glucose of lauroyl chloride and 40 minutes of reaction

time)

65

4.5 Optimum conditions for esterification of sago starch 66

4.6 Determination of DS of the starch esters 67

4.7 Mechanical properties of fatty sago starch esters 79

LIST OF FIGURES

Figure Page

2.1 Linear and branched starch polymers 6

2.2 Starch granules 9

2.3 Trunk of sago 12

2.4 Granule structure of sago starch 14

2.5 Mechanical properties testing of thin plastic sheet 22

2.6 A possible of DSC curve 24

2.7 Residual mass, Mres and oxidation temperature (To) 26

2.8 The production of poly(vinyl chloride) 28

2.9 Scheme of dehydrochlorination of PVC 30

2.10 Hydrolysis of 1 mole triglyceride to form 1 mole glycerol

and 3 moles fatty acids

34

2.11 The preparation of fatty acid chloride from palm oil based

fatty acid

34

2.12 Chemical and biochemical modifications of starch 38

3.1 Dimensions of sample 51

4.1 Esterification of sago starch by fatty acid chloride in the

presence of formic acid

57

4.2 The conversion of sago starch to starch ester 58

4.3 FT-IR spectra of (a) sago starch, (b) and (c) are esterified

sago starch with DS 0.6 and 1.2 respectively

69

4.4 FT-IR spectra of starch (a) hexanoate, (b) octanoate and (c)

lauroate with DS 1.3, 1.2 and 1.2 respectively

71

4.5 NMR spectra of (a) sago starch and (b) esterified sago

starch

72

4.6 TGA thermograms of (a) sago starch, starch (b) lauroate

with DS 0.6, (c) hexanoate, (d) octanoate and (e) lauroate

with DS 1.3, 1.2 and 1.2 respectively

74

4.7 DSC thermogram of native sago starch 76

4.8 DSC thermograms of starch (a) hexanoate, (b) octanoate

(c) lauroate with DS 1.3, 1.2 and 1.2 respectively

76

4.9 The appearance of pure PVC film and starch ester/PVC

blend film

80

4.10 FT-IR spectra of (a) starch lauroate DS 1.3, (b) starch

lauroate/PVC of 50/50 blends and (c) PVC

82

4.11 TGA thermograms of PVC, starch hexanoate (DS 1.3) and

starch hexanoate DS 1.3/PVC blends

84

4.12 TGA thermograms of PVC, starch octanoate (DS 1.2) and

starch octanoate DS 1.2/PVC blends

84

4.13 TGA thermograms of PVC, starch lauroate (DS 1.2) and

starch lauroate DS 1.2/PVC blends

85

4.14 TGA thermograms of 50/50 of starch esters/PVC blends

and pure PVC

85

4.15 DSC thermograms of PVC and starch hexanoate DS

1.3/PVC blends

87

4.16 DSC thermograms of PVC and starch octanoate DS

1.2/PVC blends

87

4.17 DSC thermograms of PVC and starch lauroate DS 1.2/PVC

blends

88

4.18 DSC thermograms of 70/30 of starch esters/PVC blends

and pure PVC

88

4.19 Tensile strength at break of blends of starch lauroate DS

0.6 (STLC0.6), starch hexanoate DS 1.3 (STHC1.3), starch

octanoate DS 1.2 (STOC1.2) and starch lauroate DS1.2

(STLC1.2) with PVC

91

4.20 Relative tensile strength of blends of starch lauroate DS 0.6

(STLC0.6), starch hexanoate DS 1.3 (STHC1.3), starch

octanoate DS 1.2 (STOC1.2) and starch lauroate DS 1.2

(STLC1.2) with PVC

91

4.21 Elongation at break of blends of starch lauroate DS 0.6

(STLC0.6), starch hexanoate DS 1.3 (STHC1.3), starch

octanoate DS 1.2 (STOC1.2) and starch lauroate DS 1.2

(STLC1.2) with PVC

93

4.22 Relative elongation at break of blends of starch lauraote

DS 0.6 (STLC0.6), starch hexanoate DS 1.3 (STHC1.3),

starch octanoate DS 1.2 (STOC1.2) and starch lauroate DS

1.2 (STLC1.2) with PVC

93

4.23 Water absorption versus time of starch hexanoate DS

1.3/PVC blends

95

4.24 Water absorption versus time of starch octanoate DS

1.2/PVC blends

95

4.25 Water absorption versus time of starch lauroate DS

1.2/PVC blends

96

4.26 Water absorption of 50/50 of starch hexanoate DS 1.3/PVC

(STHC1.3), starch octanoate DS 1.2/PVC (STOC1.2),

starch lauroate DS 1.2/PVC (STLC1.2) and starch lauroate

DS 0.6 (STLC0.6)/PVC blends and pure PVC

96

4.27 Weight loss of starch hexanoate DS 1.3/PVC blends during

immersion in sludge

99

4.28 Weight loss of starch octanoate DS 1.2/PVC blends during

immersion in sludge

99

4.29 Weight loss of starch lauroate DS 1.2/PVC blends during

immersion in sludge

100

4.30 Weight loss of 50/50 of starch hexanoate DS 1.3/PVC

(STHC1.3), starch octanoate DS 1.2/PVC (STOC1.2),

starch lauroate DS 1.2/PVC (STLC1.2) and starch lauroate

DS 0.6/PVC (STLC0.6) blends and pure PVC

100

LIST OF ABBREVIATIONS

ASTM The American Society for Testing and Materials

CPKO Crude palm kernel oil

CPO Crude palm oil

DS Degree of substitution

DSC Differential Scanning Calorimeter

DMSO Dimethyl sulfoxide

EDC Ethylene dichloride

et al. et alia (and others)

FT-IR Fourier Transform Infrared

GPa Giga pascal

ha Hectare

HCl Hydrochloric acid

LDPE Low density polyethylene

Mpa Mega pascal

Mres Residual mass

NMR Nuclear Magnetic Resonance

psi Pounds per square inch

PVC Poly(vinly chloride)

spp. Species (more than one)

t Time

T Temperature

Td Decomposition temperature

Tg Glass transition temperature

TGA Thermogravimetric analysis

THF Tetrahydrofuran

Tm Melt transition temperature

To Oxidation temperature

VC Vinyl chloride

wt % Percentage of weight

> More than

< Less than

CHAPTER 1

INTRODUCTION

1.1 General Review

Today, plastic industries are concerning about the biodegradability of their

petroleum-based products before bring them to the market place. Virtually no

synthetic plastic is totally biodegradable. It is highly resistant to microbial attack

and is the major cause of the environmental problems. Replacement of synthetic

plastics with materials from agro resources, especially starch, is attractive

because of providing biodegradation properties.

However, starch by itself is unsuitable for most uses as a plastic because of its

poor physical and chemical properties. Some approaches to overcoming these

problems include physical and chemical modifications. For example, long chain

esters of starch with high degree of substitution (DS) from chemical modification

have interesting thermoplastic properties (Aburto et al., 1999a).

Actually, utilization of modified starch in the plastics industry is not new.

Interest in the preparation of chemically or physically modified starches remains

high (Aburto et al., 1999a; Kiatamjornwong et al., 2001; Sang and Lim, 1998)

despite the fact that the vast majority of commercially available modified

starches today are based on the work carried out in the 1940s and 1950s (Fang et

al., 2002).

1.2 Justification of the Study

Biodegradable plastics offer a solution to the growing disposal problem of

petroleum-based plastics. The greatest part of the plastic waste derived from

packaging and building constructions for which recycling are neither practical

nor economical. The choices for dealing with this waste are limited as

incineration of plastic polymers results in the generation of toxic emissions; the

only viable solution is to bury the material in landfills. However, this approach is

also limited because of the resistant nature of plastic to biological degradation.

So, the productions of biodegradable starch plastics are desirable.

Substitution of petroleum based plastics with starch plastic would permit us to

conserve our petrochemical resources and to find out new non-food uses for

starch. Starch is inexpensive, abundance and is produced in greater quantities

than current market demand (Shogren et al., 1993).

Biodegradable starch plastics can be prepared in numerous ways include

chemical and physical means. One of the chemical modifications is

esterification. Lipophilic substitution of hydroxyl groups of starch with alkyl

groups in organic solvent medium has produced starch ester. High degree

substitution of starch esters behaves as thermoplastic properties, but their high