5.1 introductionshodhganga.inflibnet.ac.in/bitstream/10603/34626/15/15_chapter5.pdf5.2.1 synthesis...

Chapter – 5

Page | 197

The present chapter deals with the synthesis of interpenetrating

polymer networks from epoxy ester polyol based polyurethane (EPU) and

various acrylate monomers. Epoxy ester polyol was prepared from epoxy

resin (DGEBA) and ricinoleic acid. Prepared IPN syrups were casted into

glass cavity for film formation. The prepared casted films were

characterized by thermogravimetric analysis (TGA), scanning electron

microscopy (SEM) and dyanamic mechanical analysis (DMA).

5.1 INTRODUCTION

Epoxy resins are well known for their excellent physico-chemical

properties and are chiefly used as adhesives, laminates, boards, molds for

casting and composite materials in the aerospace and aircraft industries.

In addition to these applications, they find their substantial applications in

high performance surface coatings. Coatings from epoxies have been

found to show marked resistance to chemicals and corrosive

environments. However, these coatings fail to give satisfactory

performance under strained conditions. Recently, vigorous interest has

been shown in the modification of epoxies to overcome short comings

such as low toughness, poor weathering resistance, low thermal stability,

poor pigment holding ability, and yellowing.

Today’s technology of epoxy resins had started only by late 1930’s

and early 1940s, when a number of patents were applied simultaneously

in U.S.A. and Europe. Special mention may be made of the work carried

out by Dr. Castan of Switzerland and Dr. Sylvan Greenlee of the United

States simultaneously around the year 1938, who had patented the first

epoxy resin out of reaction of epichlorohydrin and bisphenol-A.

Subsequently, in the early 1940s, CIBA A G of Basle took the

authorization of patent by Greenlee et al.

Chapter – 5

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Figure 5.1: Typical structure of DGEBA

Various types of epoxy resins have been produced: glycidyl ethers,

glycidylamines, linear aliphatics and cycloaliphatics. However, epoxy

resin, which is a reaction product of epichlorohydrin and bisphenol-A, is

most commonly used epoxy resin today, known as diglycidyl ether of

bisphenol-A (DGEBA) (Figure 5.1)

The resin can be obtained with different degrees of polymerization

ranging from low viscosity liquids to high melting solids [1].

In order to prepare high molecular weight resin and to avoid

contamination the epoxy resin can be prepared by two-stage process. This

involves first the preparation of lower molecular weight polymers with a

degree of polymerization of about three and then reacted with bisphenols-

A in the presence of a suitable polymerization catalyst such that the

reaction takes place without evolution of by product [2].

The epoxide resins of the glycidyl ether are usually characterized

by six parameters:

Resin viscosity (of liquid resin)

Epoxide equivalent

Hydroxyl equivalent

Average molecular weight

Chapter – 5

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Melting point (of solid resin)

Heat distortion temperature (of cured resin)

The epoxy resin can be converted into three dimensional infusible

networks together by covalent bonds. This conversion from a liquid or a

friable brittle solid into tough cross-linked polymer is called curing or

hardening in epoxy technology. Mainly amine hardening and acid

hardening systems are employed for curing of epoxy resins.

Epoxy resins are widely used for land, marine and space

transportation, automobile and electrical components, rehabilitations

products and pollution control equipments. The characteristic properties

of epoxy resins make them suitable for an increasing number of

engineering applications, such as high strength and stiffness, good

dielectric behavior, resistance to chemicals, low shrinkage during cure,

etc. Despite of excellent properties their brittle behavior with low

elongation restricts their use for high performance applications [3].

Many researchers have tried to modify the epoxy resin to improve its

mechanical properties by reacting it with dienes [4], acrylates, etc. This

modification of epoxy resin is feasible due to highly reactive epoxy ring,

which can also undergo ring opening reaction in the presence of acids [5]

to yield polyester polyol containing a free hydroxyl group that can be

utilized to produce polyurethanes.To make an economic production of

polyurethanes, efforts have been made to prepare polyester polyols from

the low cost natural oils and their derivatives.

Epoxy resins are increasingly being used in industry. Research and

developments in this area are expanding significantly. Efforts are being

made to develop epoxy resins with better toughness characteristics,

lower viscosity, reduced shrinkage during cure and lower moisture

Chapter – 5

Page | 200

absorption [6, 7]. Recent developments in epoxy resins include the

synthesis of new epoxy resins with better structural properties.

The curing of epoxy resins using amines, anhydride,

(uncatalysed or catalysed), polyamides etc. have been reported in the

literature. However to the best of our knowledge no reports are

available using mixture of dianhydride and amines. It was therefore

considered of interest to investigate systematically the curing

behaviour of epoxy resins in the presence of anhydrides/or

dianhydride of varying structure in the presence/absence of aromatic

diamine and benzoxazine monomers of varying structures.

5.1.1 Types of Epoxy resin

5.1.1.1 Diglycidyl Resins

These are difunctional epoxy resins which are characterised

by the presence of two oxirane groups per molecule of resin. The

most important commercial epoxide is based on bisphenol-A. These

are general purpose resins and can be used for a variety of

applications. The synthesis of these resins involve reaction of bisphenol-

A with excess of epichlorohydrin in the presence of a base [8-10] (Figure

5.2)

The preparation of glycidyl ether of 1, 2-, 1, 3- and 1, 4-

benzene diols and other mononuclear dihydric phenols has also been

reported [11]. Dinuclear dihydric phenols with single atom between

the aromatic rings have been used for the preparation of epoxy

resins [12].These types of diols can be readily prepared by the reaction of

a wide variety of aldehydes and ketones with substituted/ unsubstituted

phenols [13].

Chapter – 5

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Figure 5.2: Typical reaction scheme for diglycidyl ether for bisphenol-A

(DGEBA)

Glycidyl esters from acids such as phthalic and hydrogenated

phthalic acids have been prepared by reacting these acids and

epichlorohydrin followed by dehydrohalogenation with sodium

hydroxide (Figure 5.3).

Figure 5.3: Reaction scheme for glycidyl esters from acids

Chapter – 5

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Glycidyl ester derivatives prepared from benzophenone

tetracarboxylic acid dianhydride (BTDA) were soluble in highly polar

organic solvents and had processing characteristics comparable to

epoxies [14]. An intermediate dimide acid is obtained from the

reaction of BTDA and amino acids which on treatment with

epichlorohydrin (using quaternary ammonium halide as catalyst) gave

diglycidyl esters (Figure 5.3). The imide group in the resins improved

thermal stability.

Figure 5.3: Structure of glycidyl ester prepared from BTDA.

Heat resistant aromatic imide epoxy esters (Figure 5.4) have

been synthesised by Saito et al 21,22 starting from trimellitic acid

anhydride and 3,3’-diaminodiphenyl sulfone followed by reaction with

epichlorohydrin in the presence of quaternary ammonium salt.

Figure 5.4: Structure of heat resistanct aromatic imide epoxy esters.

Chapter – 5

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5.1.1.2 Multifunctional epoxy resin

In order to produce resins of high heat distortion temperature,

it is important to have a high crosslink density and rigid segments

between the crosslinks. The triglycidyl resins of p-aminophenol are

low viscosity liquids, had fast cure rate, excellent processability,

better thermal resistance and good mechanical properties. These

resins are useful as adhesives, coatings, laminates and composites.

The triglycidylether of tris (4-hydroxyphenyl) methane [15], tris (2-

hydroxy-hexafluoro-2-propyl) methane [16] and 4-(4-amino-α,α-

dimethylbenzyl) phenol [17] have been developed for performance

enhancement. The glycidylation of cyanuric acid with epichlorohydrin

gives triglycidyl isocyanurate. It is a crystalline compound with

melting point of 85-110ºC and an epoxy equivalent of 108. A liquid

compound having good shelf life, good heat and water resistance,

prepared from benzene triol and epichlorohydrin/substituted

epichlorohydrin has been patented (Figure 5.5) [18].

Figure 5.5

Chapter – 5

Page | 204

5.1.1.3 Cycloaliphatic epoxy resins

The epoxidation of unsaturated compounds with peracids is

used in the manufacture of cycloaliphatic epoxy resins (Figures 5.6 -

5.8) [19]. Cycloaliphatic epoxy resins do not contain aromatic

compounds and hence are more stable to ultra-violet exposure than

bisphenol-A derived epoxy resins.

Figure 5.6: Structure of 4', 4’-epoxycyclohexylmethyl-3, 4 -

epoxycyclohexane carboxylate

Figure 5.7: Structure of 1', 2'-epoxyethyl-3, 4 – epoxycyclohexane

Figure 5.8: Structure of dicyclopentadiene containing epoxy

Chapter – 5

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5.1.1.4 Flame Retardant Epoxy Resins

Epoxy resins with improved flame resistance can be prepared by

reacting 4, 4’-diglycidyl ether of bisphenol A (DGEBA) with dialkyl

(or aryl) phosphate. Curing of these resins was done in the presence

of 4, 4’-diaminodiphenyl sulfone (DDS). By the reaction of DGEBA

with dialkyl (or aryl) phosphate, it is also possible to incorporate

phosphorus in the epoxy resin. Flammability and thermal behavior of

modified DGEBA/DDS resin depend on the nature of phosphate groups

and their concentration in the material [20].

The oxaphosphorin-6-[2,5-bis-oxi-ranylmethoxy)phenyl]-6-oxide

(DOPO epoxy resin) [21] (Figure 5.9), expected to exhibit the

required flame retardancy, less fumes and more thermal stability than

the halogen containing conventional flame-retardant epoxy resin.

Figure 5.9: Structure of oxaphosphorin-6-[2,5-bis-oxi-

ranylmethoxy)phenyl]-6-oxide (DOPO epoxy resin)

Chapter – 5

Page | 206

5.2 EXPERIMENTAL

5.2.1 Synthesis of epoxy ester based polyol from DGEBA and

ricinoleic acid

Reactive novel polyol-A was synthesized by reacting 2.0 mole of

ricinoleic acid having free carboxyl group with 1.0 mole of DGEBA

epoxy resin in three necked round bottom flask equipped with nitrogen

inlet and water condenser. Triethyl amine (0.05 %) catalyst was added

along with 100 ml of dioxane in the flask. The reaction was carried out at

reflux temperature of dioxane for 3.5 hours. After completion of reaction

dioxane was distilled out from the flask. At the end of reaction, a viscous

liquid was collected in clean glass stopper bottle. Reaction Scheme is

shown in Figure 5.10.

Figure 5.10: Synthesis of epoxy ester polyol (EE)

5.2.1.1 Preliminary characterization of epoxy ester polyol (EE)

Preliminary characterization of prepared epoxy ester polyol was

characterized by hydroxyl value, iodine value, epoxy equivalent, acid

value and IR spectroscopy. All these characterization were carried out as

Chapter – 5

Page | 207

method described in Chapter – 2. Data observed of the characterization

are shown in Table 5.1.

Table 5.1: Characteristic data of epoxy ester polyol (EE)

Sr. No. Properties Epoxy ester polyol

1 Acid Value 0

2 Hydroxyl value 115

3 Iodine value 49.3

4 Epoxy equivalent 0

5.2.2 Synthesis of epoxy ester based interpenetrating polymer

network

Synthesis of EEPU (A)/PMMA IPN from EEPU (A) (epoxy ester

polyol + isophorone diisocyanate) and methyl methacrylate

An epoxy ester polyol (EE) was placed in a round bottom flask. To

this epoxy ester polyol (EE), calculated amount of

isophoronediisocyanate was drop wise added in the presence of dibutyltin

dilaurate (DBTDL) as a catalyst. The mixture was stirred at room

temperature for 1 hour to form EEPU, which was abbreviated as EEPU

(EE based polyurethane). To this EEPU, stabilizer free

methylmethacrylate was added along with benzoyl peroxide (initiator), N,

N’- dimethylaniline (coinitiator) and ethylene glycol dimethacrylate

(cross linking agent). As the reaction mixture (IPN) becomes pourable

viscous liquid, it was poured in to the glass cavity without remaining air

bubble and rest of the reaction were allowed to proceed at room

temperature. A series of IPNs of different compositions were obtained by

Chapter – 5

Page | 208

varying the weight of polyurethane and methylmethacrylate monomer

following the same procedure. The finished films were cut in desired

shapes for further study and characterization. The reaction scheme is

shown in Figure 5.11. The data of feed composition is shown in Table

5.2.

Figure 5.11: Synthesis of interpenetrating polymer networks from EEPU

(Isophorone diisocyanate based) and PMMA.

Table 5.2: Data of feed composition (individual) Polyurethane (EEPU)

and Methylmethacrylate for IPN synthesis

Entry NCO/OH ratio of

IPDI and TCO

Polyurethane

(Wt. %)

Methyl methacrylate

(Wt. %)

IPN9a 2.0 90 10

IPN9b 2.0 80 20

IPN9c 2.0 70 30

IPN9d 2.0 60 40

IPN9e 2.0 50 50

IPN9f 2.0 40 60

IPN9g 2.0 30 70

IPN9h 2.0 20 80

IPN9i 2.0 10 90

Chapter – 5

Page | 209

Synthesis of EEPU (A)/PAN IPN from EEPU (A) (epoxy ester polyol

+ isophorone diisocyanate) and acrylonitrile






(EE based polyurethane). To this EEPU, acrylonitrile was added along

with benzoyl peroxide (initiator), N, N’- dimethylaniline (coinitiator) and

ethylene glycol dimethacrylate (cross linking agent). As the reaction

mixture (IPN) becomes pourable viscous liquid, it was poured in to the

glass cavity without remaining air bubble and rest of the reaction were

allowed to proceed at room temperature. A series of IPNs of different

compositions were obtained by varying the weight of polyurethane and

acrylonitrile monomer following the same procedure. The finished films

were cut in desired shapes for further study and characterization. The

reaction scheme is shown in Figure 5.12. The data of feed composition is

shown in Table 5.3.

Chapter – 5

Page | 210


(Isophorone diisocyanate based) and PAN.


and acrylonitrile for IPN synthesis


IPDI and TCO

Polyurethane

(Wt. %)

Acrylonitrile

(Wt. %)

IPN10a 2.0 90 10

IPN10b 2.0 80 20

IPN10c 2.0 70 30

IPN10d 2.0 60 40

IPN10e 2.0 50 50

IPN10f 2.0 40 60

IPN10g 2.0 30 70

IPN10h 2.0 20 80

IPN10i 2.0 10 90

Chapter – 5

Page | 211

Synthesis of EEPU (A)/PBA IPN from EEPU (A) (epoxy ester polyol

+ isophorone diisocyanate) and butyl acrylate






(EE based polyurethane). To this EEPU, stabilizer free butylacrylate was

added along with benzoyl peroxide (initiator), N, N’- dimethylaniline

(coinitiator) and ethylene glycol dimethacrylate (cross linking agent). As

the reaction mixture (IPN) becomes pourable viscous liquid, it was

poured in to the glass cavity without remaining air bubble and rest of the

reaction were allowed to proceed at room temperature. A series of IPNs

of different compositions were obtained by varying the weight of

polyurethane and butyl acrylate monomer following the same procedure.

The finished films were cut in desired shapes for further study and

characterization. The reaction scheme is shown in Figure 5.13. The data

of feed composition is shown in Table 5.4.

Chapter – 5

Page | 212


(Isophorone diisocyanate based) and PBA.


and butyl acrylate for IPN synthesis


IPDI and TCO

Polyurethane

(Wt. %)

Butyl acrylate

(Wt. %)

IPN11a 2.0 90 10

IPN11b 2.0 80 20

IPN11c 2.0 70 30

IPN11d 2.0 60 40

IPN11e 2.0 50 50

IPN11f 2.0 40 60

IPN11g 2.0 30 70

IPN11h 2.0 20 80

IPN11i 2.0 10 90

Chapter – 5

Page | 213

Synthesis of EEPU (A)/PEA IPN from EEPU (A) (epoxy ester polyol

+ isophorone diisocyanate) and ethyl acrylate






(EE based polyurethane). To this EEPU, stabilizer free ethyl acrylate was

added along with benzoyl peroxide (initiator), N, N’- dimethylaniline

(coinitiator) and ethylene glycol dimethacrylate (cross linking agent). As

the reaction mixture (IPN) becomes pourable viscous liquid, it was

poured in to the glass cavity without remaining air bubble and rest of the

reaction were allowed to proceed at room temperature. A series of IPNs

of different compositions were obtained by varying the weight of

polyurethane and ethyl acrylate monomer following the same procedure.

The finished films were cut in desired shapes for further study and

characterization. The reaction scheme is shown in Figure 5.14. The data

of feed composition is shown in Table 5.5.

Chapter – 5

Page | 214


(Isophorone diisocyanate based) and PEA.


and ethyl acrylate for IPN synthesis


IPDI and TCO

Polyurethane

(Wt. %)

Ethyl acrylate

(Wt. %)

IPN12a 2.0 90 10

IPN12b 2.0 80 20

IPN12c 2.0 70 30

IPN12d 2.0 60 40

IPN12e 2.0 50 50

IPN12f 2.0 40 60

IPN12g 2.0 30 70

IPN12h 2.0 20 80

IPN12i 2.0 10 90

Chapter – 5

Page | 215

Synthesis of EEPU (A)/PMMA IPN from EEPU (A) (epoxy ester

polyol + toluene diisocyanate) and methyl methacrylate


this epoxy ester polyol (EE), calculated amount of toluenediisocyanate

was drop wise added in the presence of dibutyltin dilaurate (DBTDL) as a

catalyst. The mixture was stirred at room temperature for 1 hour to form

EEPU, which was abbreviated as EEPU (EE based polyurethane). To this

EEPU, stabilizer free methylmethacrylate was added along with benzoyl

peroxide (initiator), N, N’- dimethylaniline (coinitiator) and ethylene

glycol dimethacrylate (cross linking agent). As the reaction mixture (IPN)

becomes pourable viscous liquid, it was poured in to the glass cavity

without remaining air bubble and rest of the reaction were allowed to

proceed at room temperature. A series of IPNs of different compositions

were obtained by varying the weight of polyurethane and methylmetha

acrylate monomer following the same procedure. The finished films were

cut in desired shapes for further study and characterization. The reaction

scheme is shown in Figure 5.15. The data of feed composition is shown

in Table 5.6.

Chapter – 5

Page | 216


(toluene diisocyanate based) and PMMA


and methyl methacrylate for IPN synthesis


TDI and TCO

Polyurethane

(Wt. %)

Methyl methacrylate

(Wt. %)

IPN13a 2.0 90 10

IPN13b 2.0 80 20

IPN13c 2.0 70 30

IPN13d 2.0 60 40

IPN13e 2.0 50 50

IPN13f 2.0 40 60

IPN13g 2.0 30 70

IPN13h 2.0 20 80

IPN13i 2.0 10 90

Chapter – 5

Page | 217

Synthesis of EEPU (A)/PAN IPN from EEPU (A) (epoxy ester polyol

+ toluene diisocyanate) and acrylonitrile






EEPU, acrylonitrile was added along with benzoyl peroxide (initiator), N,

N’- dimethylaniline (coinitiator) and ethylene glycol dimethacrylate

(cross linking agent). As the reaction mixture (IPN) becomes pourable

viscous liquid, it was poured in to the glass cavity without remaining air

bubble and rest of the reaction were allowed to proceed at room

temperature. A series of IPNs of different compositions were obtained by

varying the weight of polyurethane and acrylonitrile monomer following

the same procedure. The finished films were cut in desired shapes for

further study and characterization. The reaction scheme is shown in

Figure 5.16. The data of feed composition is shown in Table 5.7.

Chapter – 5

Page | 218


(toluene diisocyanate based) and PAN


and acrylonitrile for IPN synthesis


TDI and TCO

Polyurethane

(Wt. %)

Acrylonitrile

(Wt. %)

IPN14a 2.0 90 10

IPN14b 2.0 80 20

IPN14c 2.0 70 30

IPN14d 2.0 60 40

IPN14e 2.0 50 50

IPN14f 2.0 40 60

IPN14g 2.0 30 70

IPN14h 2.0 20 80

IPN14i 2.0 10 90

Chapter – 5

Page | 219


+ toluene diisocyanate) and butyl acrylate






EEPU, stabilizer free butyl acrylate was added along with benzoyl






were obtained by varying the weight of polyurethane and butyl acrylate

monomer following the same procedure. The finished films were cut in

desired shapes for further study and characterization. The reaction


in Table 5.8.

Chapter – 5

Page | 220


(toluene diisocyanate based) and PBA


and butyl acrylate for IPN synthesis


TDI and TCO

Polyurethane

(Wt. %)

Butyl acrylate

(Wt. %)

IPN15a 2.0 90 10

IPN15b 2.0 80 20

IPN15c 2.0 70 30

IPN15d 2.0 60 40

IPN15e 2.0 50 50

IPN15f 2.0 40 60

IPN15g 2.0 30 70

IPN15h 2.0 20 80

IPN15i 2.0 10 90

Chapter – 5

Page | 221


+ toluene diisocyanate) and ethyl acrylate






EEPU, stabilizer free ethyl acrylate was added along with benzoyl






were obtained by varying the weight of polyurethane and ethyl acrylate

monomer following the same procedure. The finished films were cut in

desired shapes for further study and characterization. The reaction


in Table 5.9.

Chapter – 5

Page | 222


(toluene diisocyanate based) and PEA


and ethyl acrylate for IPN synthesis


TDI and TCO

Polyurethane

(Wt. %)

Ethyl acrylate

(Wt. %)

IPN16a 2.0 90 10

IPN16b 2.0 80 20

IPN16c 2.0 70 30

IPN16d 2.0 60 40

IPN16e 2.0 50 50

IPN16f 2.0 40 60

IPN16g 2.0 30 70

IPN16h 2.0 20 80

IPN16i 2.0 10 90

Chapter – 5

Page | 223

5.3 CHARACTERIZATION OF EPOXY ESTER

POLYURETHANE BASED IPNs

Damping, thermal and morphological properties of previously

prepared IPNs were measured. The thermal analysis of IPNs was

accompanied by thermogravimetric analysis (TGA), damping properties

were measured by dynamic mechanical analysis (DMA), while

morphological analysis was evaluated by scanning electron microscopy

(SEM).

5.3.1 Dynamic mechanical analysis

5.3.1.1 Experimental

Dynamic mechanical analysis (DMA) is performed on a Triton

Technology Ltd, U.K. Tritec2000 model Instrument. Specimen in the

form of strips (~60 mm long, 13 mm wide,1.5mm to 1.7 mm thick) are

tested in a three-point bending mode (span length 50 mm).The specimen

was heated at rate of 10oC/min. The frequencies used were 10 Hz. The

storage modulus (G’) and the loss tangent (tanδ) were obtained as a

function of temperature. The glass transition temperature (Tg) of the UV

coating films was obtained from the peaks of the loss tangent (tanδ)

curve. The dynamic mechanical properties of these IPNs have been

evaluated by the tanδ maximum. All the obtained data from dynamic

mechanical analysis is given in Figures 5.19 – 5.26 and Tables 5.10 –

5.17.

Chapter – 5

Page | 224

Figure 5.19: DMA curve of IPN 9 (EEPU/PMMA by using Isophorene

diisocyanate)

Table 5.10: DMA data of IPN 9 (EEPU/PMMA by using Isophorene

diisocyanate) at 10Hz frequency.

Sample

Code

% weight components Temp.range

(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PMMA

IPN-9a 90 10 59.7-153.5 1.5420 100.2

IPN-9b 80 20 55.2-156.8 1.4521 101.3

IPN-9c 70 30 57.2-158.6 1.4021 103.4

IPN-9d 60 40 52.3-160.2 1.3745 104.2

IPN-9e 50 50 44.2-165.4 1.3260 104.9

IPN-9f 40 60 57.8-158.2 1.2832 105.2

IPN-9g 30 70 53.7-166.9 1.2614 105.2

IPN-9h 20 80 60.2-158.6 1.2354 105.9

IPN-9i 10 90 60.8-168.1 1.2036 106.3

Chapter – 5

Page | 225

Figure 5.20: DMA curve of IPN 10 (EEPU/PAN by using Isophorene

diisocyanate)

Table 5.11: DMA data of IPN 10 (EEPU/PAN by using Isophorene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PAN

IPN-10a 90 10 59.7-153.5 1.5021 98.2

IPN-10b 80 20 53.1-153.5 1.4725 99.5

IPN-10c 70 30 56.4-156.2 1.4421 101.3

IPN-10d 60 40 50.6-142.6 1.4021 102.1

IPN-10e 50 50 42.8-163.3 1.3625 102.9

IPN-10f 40 60 55.4-156.3 1.3256 103.5

IPN-10g 30 70 51.3-165.7 1.3012 104.1

IPN-10h 20 80 58.9-167.8 1.2756 104.8

IPN-10i 10 90 60.8-168.1 1.2356 106.2

Chapter – 5

Page | 226

Figure 5.21: DMA curve of IPN 11 (EEPU/PBA by using Isophorene

diisocyanate)

Table 5.12: DMA data of IPN 11 (EEPU/PBA by using Isophorene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PBA

IPN-11a 90 10 60.7-154.5 1.5236 99.2

IPN-11b 80 20 55.1-156.5 1.4958 100.2

IPN-11c 70 30 58.4-158.2 1.4658 101.9

IPN-11d 60 40 52.6-145.6 1.4256 102.7

IPN-11e 50 50 44.8-165.3 1.3825 103.4

IPN-11f 40 60 58.4-159.3 1.3526 104.1

IPN-11g 30 70 53.3-168.7 1.3125 104.6

IPN-11h 20 80 60.9-169.8 1.2603 105.0

IPN-11i 10 90 62.8-169.1 1.2306 105.2

Chapter – 5

Page | 227

Figure 5.22: DMA curve of IPN 12 (EEPU/PEA by using Isophorene

diisocyanate)

Table 5.13: DMA data of IPN 12 (EEPU/PEA by using Isophorene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PEA

IPN-12a 90 10 63.7-155.5 1.4857 96.2

IPN-12b 80 20 55.1-157.5 1.4526 97.2

IPN-12c 70 30 58.4-159.2 1.4125 98.2

IPN-12d 60 40 52.6-145.6 1.3625 99.1

IPN-12e 50 50 45.8-165.3 1.3205 100.1

IPN-12f 40 60 58.4-160.3 1.2915 100.7

IPN-12g 30 70 53.3-168.7 1.2645 101.8

IPN-12h 20 80 60.9-169.8 1.2153 102.5

IPN-12i 10 90 62.8-170.1 1.1825 103.2

Chapter – 5

Page | 228

Figure 5.23: DMA curve of IPN 13 (EEPU/PMMA by using Toluene

diisocyanate)

Table 5.14: DMA data of IPN 13 (EEPU/PMMA by using Toluene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PMMA

IPN-13a 90 10 61.7-156.5 1.5723 101.3

IPN-13b 80 20 55.1-156.5 1.5362 102.3

IPN-13c 70 30 58.4-160.2 1.5089 103.6

IPN-13d 60 40 56.6-147.6 1.4526 104.5

IPN-13e 50 50 48.8-165.3 1.4021 105.1

IPN-13f 40 60 58.4-159.3 1.3226 105.8

IPN-13g 30 70 54.3-168.7 1.3012 106.4

IPN-13h 20 80 61.9-169.8 1.2854 107.1

IPN-13i 10 90 63.8-170.1 1.2536 107.5

Chapter – 5

Page | 229

Figure 5.24: DMA curve of IPN 14 (EEPU/PAN by using Toluene

diisocyanate)

Table 5.15: DMA data of IPN 14 (EEPU/PAN by using Toluene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PAN

IPN-14a 90 10 61.7-155.5 1.5326 99.0

IPN-14b 80 20 55.1-156.5 1.5021 99.9

IPN-14c 70 30 58.4-159.2 1.4823 100.5

IPN-14d 60 40 52.6-145.6 1.4521 101.2

IPN-14e 50 50 45.8-166.3 1.4125 101.9

IPN-14f 40 60 57.4-159.3 1.3856 102.6

IPN-14g 30 70 53.3-167.7 1.3525 103.1

IPN-14h 20 80 60.9-169.8 1.3365 103.8

IPN-14i 10 90 62.8-170.1 1.3025 104.5

Chapter – 5

Page | 230

Figure 5.25: DMA curve of IPN 15 (EEPU/PBA by using Toluene

diisocyanate)

Table 5.16: DMA data of IPN 15 (EEPU/PBA by using Toluene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PBA

IPN-15a 90 10 60.7-155.5 1.5485 100.2

IPN-15b 80 20 55.1-157.5 1.5198 100.9

IPN-15c 70 30 58.4-159.2 1.4958 102.4

IPN-15d 60 40 52.6-145.6 1.4725 103.2

IPN-15e 50 50 44.8-165.3 1.4425 104.1

IPN-15f 40 60 58.4-159.3 1.4185 104.8

IPN-15g 30 70 53.3-167.7 1.3825 105.2

IPN-15h 20 80 60.9-168.8 1.3526 106.1

IPN-15i 10 90 61.8-169.1 1.3152 106.8

Chapter – 5

Page | 231

Figure 5.26: DMA curve of IPN 16 (EEPU/PEA by using Toluene

diisocyanate)

Table 5.17: DMA data of IPN 16 (EEPU/PEA by using Toluene


Sample

Code


(0C) Tanδ

Tanδ

(max) Tg in (

0C)

%EEPU %PEA

IPN-16a 90 10 60.7-156.5 1.5123 97.5

IPN-16b 80 20 55.1-156.5 1.4836 98.2

IPN-16c 70 30 58.4-159.2 1.4525 99.6

IPN-16d 60 40 55.6-147.6 1.4251 100.5

IPN-16e 50 50 45.8-166.3 1.3956 101.2

IPN-16f 40 60 57.4-158.3 1.3685 102.1

IPN-16g 30 70 53.3-167.7 1.3365 102.9

IPN-16h 20 80 60.9-169.8 1.3125 103.9

IPN-16i 10 90 63.8-170.1 1.2845 104.7

Chapter – 5

Page | 232

5.3.1.2 Results and discussion

Figures 5.18 – 5.26 and Tables 5.10 – 5.17 are showing the data of

epoxy ester polyurethane and various acrylates based IPNs with different

components at 10Hz and DMA curve. We have tried to find out the

various mechanical damping properties of IPNs by taking different

%weight ratio of both polymers used in the IPN preparation. Dynamic

mechanical analysis or dynamic mechanical thermal analysis (DMTA) is

useful method for determination of elastic and loss modulus of polymers

as a function of temperature, frequency or time, or both. The dyanamic

mechanical analysis were characterised by storage modulus (E’), loss

modulus (E”) and loss factor (tanδ), which can be elaborated by the ratio

of loss modulus to storage modulus. All the shown three parameters are

the function of temperature and frequencies. Normally magnitude of tanδ

can be used to predict the damping behaviour of the polymeric material

[22]. This property can be the essential property for the material

selection, as an example we can consider shock absorber property, higher

values of damping leads to the higher energy absorption. Generally

materials which are having high and wide loss factor peak can be used as

good damping materials.

It can be seen from Figures 5.18 – 5.26 that there is much

influence of the value of tanδ as the %weight ratio of acrylate increases

while Tg gets decreased as increasing the %weight ratio of acrylates. It

also seen from Figures 5.18 – 5.26 that temperature for peak of the tanδ

becomes much lower as the increase in the acrylate content. It can also be

observed from the figure that all the composition is showing the single

value of tanδ. This is attributed to the homogeneous composition [23].

Chapter – 5

Page | 233

5.3.2 Thermogravimetric analysis

5.3.2.1 Experimental

TA instrument Model-2960 Thermogravimetric analyzer was used

in the present study to record the thermograms of polymer samples. The

sample container i.e., the boat made from aluminium foil which would

hold the polymeric sample for the thermal analysis was washed properly

and dried. It was suspended on the quartz rod in the thermobalance of TG

instrument. The sample (about 8 to 10mg) was placed in the boat and

suspended on the quartz rod in an atmosphere of air. The weight of the

sample was noted on TGA balance. The whole assembly was brought into

the furnace. It was ascertained that the boat was hanging on the quartz

rod. The experiment was started by heating the system at constant and

definite rate throughout the experiment. Simultaneous change in weight

was recorded automatically with time where temperature was increased at

a known uniform rate. This will reveal loss in weight of material as a

function of time and also temperature. The experiment was stopped when

no further change in weight could be observed on further heating. Heating

rate was maintained at 10 0C/min. TA thermograms of IPN films are

shown in Figures 5.27 – 5.34 and data of TGA analysis are shown in

Tables 5.18 – 5.25.

The calculated data of thermograms of interpenetrating polymer

networks i.e. % of weight loss at different temperature (2500C, 300

0C,

3500C, 400

0C, 450

0C, 500

0C, 550

0C), decomposition temperature range,

the activation energy (Ea) have measured.

Chapter – 5

Page | 234

Figure 5.27: Thermograms of IPN 9a, IPN 9e, IPN 9i and pure epoxy

Table 5.18: Thermogravimetric data of IPN 9a, IPN 9e, IPN 9i and pure

epoxy

Sample

Code

Percent weight loss at different temperature 0C Activation

energy

(E) K.

cal/mole 350 400 450 500 550 600

IPN 9a 2 20 52 79 87 90 6.21

IPN 9e 3 28 62 81 89 91 7.01

IPN 9i 9 38 71 86 90 91 7.89

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 235


Table 5.19: Thermogravimetric data of IPN 10a, IPN 10e, IPN 10i and

pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 10a 2 23 60 81 89 91 6.89

IPN 10e 6 33 69 84 90 92 7.92

IPN 10i 10 44 76 88 91 92 8.51

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 236



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 11a 3 25 56 83 90 91 6.55

IPN 11e 5 32 65 85 90 92 7.01

IPN 11i 9 40 75 89 92 93 7.95

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 237



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 12a 2 21 56 80 87 89 6.40

IPN 12e 3 30 65 83 89 90 6.80

IPN 12i 9 42 71 86 90 91 7.98

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 238



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 13a 1 18 50 78 85 88 5.55

IPN 13e 2 26 60 81 89 90 6.20

IPN 13i 7 37 70 87 90 91 6.89

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 239



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 14a 1 23 53 81 87 86 5.89

IPN 14e 4 30 63 83 85 88 6.42

IPN 14i 9 40 74 87 89 90 7.01

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 240



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 15a 1 16 45 75 86 88 5.01

IPN 15e 2 22 57 81 87 89 5.65

IPN 15i 4 31 66 85 89 90 6.32

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 241



pure epoxy

Sample

Code


energy (E)

K.

cal/mole 350 400 450 500 550 600

IPN 16a 1 17 48 75 85 88 5.23

IPN 16e 3 21 57 80 88 89 5.68

IPN 16i 5 32 68 84 90 91 6.35

Pure

Epoxy 16 51 81 91 95 96 12.20

Chapter – 5

Page | 242

5.3.3.2 Results and discussion

The weight loss undergone by various interpenetrating polymer

networks at 3500C, 400

0C, 450

0C, 500

0C, 550

0C, 600

0C temperatures are

shown as TG thermograms in Figures 5.27 – 5.34.

Examination of TG thermograms of all interpenetrating polymer

networks shows a characteristic behavior of thermal degradation.

Examination of TG thermograms revealed that all the synthesized

interpenetrating polymer networks are quite stable up to 350 0C; however

the temperature of thermal stability gets changed in the series depending

upon the structural variations in the interpenetrating polymer networks.

Thus the thermal stability of these interpenetrating polymer networks was

assessed on the basis of the structural variations in the individual

component network as well as compositional change in the

interpenetrating polymer networks.

All these IPNs have found to be stable up to 350 0C; up to which

weight loss occurred only around 1 - 9%. The major step of

decomposition starts at around 400 0C; with weight loss around 16 - 44

%; depending upon the polyurethane (EEPU) content and the used

acrylate monomer. These IPNs lost their weight quite rapidly in the

region of 450 0C with the loss in the amount of more than 70 % in almost

all IPNs. The final decomposition was observed around 500 – 600 0C; all

the interpenetrating polymer networks left with the weight residue in the

final decomposition around 500 – 600 0C. This may be further evidenced

for their thermal stability among the interpenetrating polymer networks in

the present study.

The thermal behavior of IPNs in the present chapter have

compared with pure epoxy.All the IPNs have found thermally more stable

Chapter – 5

Page | 243

than pure epoxy. Interpenetration of both the component networks in the

synthesis of IPNs, results into higher thermal stability and slower rate of

their decomposition over a wide range of temperature. Another important

results have found in this thermal analysis that IPNs prepared from epoxy

ester based polyols are more thermally stable that those of prepared from

transesterified castor oil based polyols. But these IPNs are brittle in

nature.

5.4 MORPHOLOGICAL PROPERTIES OF IPN BY SCANNING

ELECTRON MICROSCOPY (SEM)

5.4.1 Experimental

The series of interpenetrating polymer networks prepared

previously in this chapter were undergone for surface morphology by

SEM. From each series, selected samples were used for the analysis.

Scanning electron microscopy (SEM) was conducted with a Joel JSM-

6380 LV model. The voltage acceleration was of 20 KV. The samples

were sputtered with gold to avoid electrostatic charges and to improve

image resolution. Images are shown in Figures 5.36 – 5.39.

Chapter – 5

Page | 244

Figure 5.36: Scanning electron micrograph (× 1,000 magnifications) of

IPN 10e


IPN 12e

Chapter – 5

Page | 245


IPN 14e


IPN 16e

Chapter – 5

Page | 246

5.4.2 Results and discussion

The morphology (Figure 5.36 – 5.39) of these IPNs has indicated

that there are two distinct phases due to individual component networks.

A polyurethane network (EEPU) network is formed first and this

interpenetrates with the acrylate monomers (methyl methacrylate,

acrylonitrile, butyl acrylate, ethyl acrylate) during two component

network syntheses. It is also evident that there is a considerable mixing of

two components. Thus, it may be revealed from SEM studies that there is

a miscibility of the two components during IPN syntheses rather than

their phase separation.

Chapter – 5

Page | 247

REFERENCE

1. I. A. Brydson, “Plastics Materials” VIth edition, Butler Worth

Heinemann Ltd., Oxford, 1995, 722.

2. Lee, H., and Neville, K., “Epoxy Resins in their Application and

Technology”, Mc Graw-Hill New York, 1957.

3. A.F. Yee, R.A. Pearson, J. Mater. Sci. 21, 1986, 2462.

4. A.V. Cunliffe, M.B. Huglin, P.J. Pearce, D.H. Richards, Polymer 16,

1975, 654.

5. C.A. May, Epoxy Resins- Chemistry and Technology, Marcel

Dekker, New York, 1988.

6. J.N. Sultan, F. McGarry, J. Polym. Eng. Sci., 13, 1979, 29.

7. B.S. Montarnal, J.P. Pascault , H. Soutereau, Adv. in Chem. Ser.,

ACS, Washington DC, 222, 1989, 193.

8. H. Lee and K. Niville, “Handbook of Epoxy Resins”, McGraw

Hill, New York, 1967, 2.

9. M. Wismer, “Chemical Reactions in Polymers”, E. M. Fettes,

ed., Interscience, New York ,1964, 905.

10. S.A. Reines, J.R. Griffith, J.G. O’ Rear, J. Org. Chem., 35, 1970,

2772.

11. J. Kosatik, D. Muzokova, J. Novak, P. Spantenka, Czech. Pat.,

179684 1979; cf CA, 92, 1980, 59677d.

Chapter – 5

Page | 248

12. P.B. Kelly, A.J. Laindua, C.D. Marshall, J. Appl. Polym. Sci, 6,

1962, 425.

13. A. Serra, V. Cadiz, P.A. Martinez and A. Mantecon, Angew,

Makromol. Chem., 140, 1986, 113.

14. K.L. Hawthrone, F.C Henson, “Resin Chemistry II”, R. S.

Bauer, ed, Am. Chem. Soc. Symp. Ser., 221, 1983, 135.

15. R.L. Sarlen and J.R. Griffith, J. Flourine Chem., 44, 1989, 203.

16. S.A.C. Zahir, Eur. Pat. Appl. EP, 148, 1985, 117; cf CA, 104, 1986,

6566b.

17. K. Kubodera, K. Tobukuro, Jpn. Kokai Tokkyo Koho JP, 61, 377,

1986, 186; cf CA, 106 (1987) 17431.

18. C.W. Ball, L.S. Ball, M.G. Walker and W.J. Wilson, Plastic

and Polymers, 40, 1972, 290.

19. D. Derouet, F. Morvan, J.C Brosse, J. Appl. Polym. Sci., 62(11),

1996, 1855.

20. C.S. Wang and J.Y. Shieh, J. Appl. Polym. Sci., 73, 1999, 353.

21. D. Ping, Y. Wang, Polym. Plast. Technol. Eng., 49, 2010, 1310.

22. S. Chen, Q. Wang, T. Wang, Polym. Test., 30, 2011, 726.

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