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Epoxidized Glycidyl Ester of Soybean Oil as Reactive Diluent for
Epoxy Resin
Rongpeng Wang and Thomas Schuman
Department of Chemistry, Missouri University of Science and Technology, Rolla, MO 65409
Abstract
Epoxidized glycidyl esters of soybean oil (EGS) have been synthesized and used as reactive diluents for partial
replacement of a commercial, bisphenol A-based epoxy resin (DGEBA). The EGS merits include a higher epoxy
content and lower viscosity than the epoxidized triglyceride soybean oil (ESO). Thermosetting resins were
fabricated from DGEBA systems blended with various amounts of EGS and ESO, using 4-methyl-1,2-
cyclohexanedicarboxylic anhydride as a curing agent and 2-ethyl-4-methylimidazole as catalyst. The curing
behavior and glass transition were monitored by differential scanning calorimetry (DSC), the performance of
thermosetting resins was studied by measurement of thermal stability and flexural properties. The results
indicate that EGS resins provide better compatibility, intermolecular crosslinking, and yield materials that are
stronger than materials obtained using ESO. However, the EGS resin systems significantly reduce viscosity
compared to either pure DGEBA or ESO-blended DGEBA counterparts. Therefore, EGS derived from renewable
sources holds potential to enable fabrication of complex, shaped epoxy composites for structural applications.
1. IntroductionEpoxy resin is one of the most important thermosetting polymers and widely used in coatings, adhesives
and composites due to its excellent mechanical strength, outstanding chemical resistance, good thermal and
electrical properties, and low shrinkage upon cure.1 Most commercially epoxy resins are relatively high
viscosity liquids or solids. Cured pure epoxy resins are rigid and brittle materials with low impact resistance.
Adding linear elastomeric or thermoplastic additives can increase the toughness; however, this invariably
results in a corresponding decrease in resin flow and processing difficulty.2
Reactive diluents are used for reducing and controlling the viscosity of epoxy resins to improve wetting
and handling characteristics because in the liquid-moulding technologies like resin transfer moulding or
pultrusion, the viscosity and resin flow are critical to achieving a quality laminate.3 Recent trends toward lower
Correspondence to: T. Schuman ([email protected])
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VOC, higher solids epoxy formulations have also resulted in increased utilization of reactive diluents.1 Phenyl
glycidyl ether and n-butyl glycidyl ether are efficient and widely used diluents, but they have been losing
interest due to toxicity, volatility or obnoxious odor issues. Industrial trends show increasing interest in longer
chain reactive diluents, e.g., C12C14 alkyl glycidyl ethers, neopentyl glycol diglycidyl ether, diglycidyl ether of
polypropylene glycol. These longer chain reactive diluents can also behave as flexibilizing agents to increase
thermosetting polymer elongation and impact resistance, though there is often a tradeoff of tensile strength,
glass transition temperature and chemical resistance.1
Since petroleum resources are limited, polymers based on vegetable oils are of great interest because they
are renewable and can significantly contribute to a more sustainable development.4-6
Epoxidized soybean oil
(ESO) has attracted great interest because of a plentiful soybean supply in the United States and therefore of
relatively low cost. ESO can be crosslinked into thermosetting polymers by various curing agents.7
However,
due to a low oxirane content and sluggish reactivity of internal epoxy groups, the cured ESO normally has a lowcrosslinking density, resulting from partially unreacted ESO and saturated fatty acid chains that act to plasticize
and degrade the thermal and mechanical properties of cured resin.
Most ESO industrial uses are limited to nonstructural applications such as plasticizers or stabilizers for poly
vinyl chloride (PVC)8, oil-base coatings
9with low strength requirements.
10ESO has a moderate viscosity and
offers good miscibility with epoxy resins.11 So ESO or their derivatives can be used as reactive diluents for the
partial replacement of epoxy resin to decrease the overall cost and improve the processability.2,12,13 Generally,
the mechanical strengths of ESO blended resins are not comparable to those of pure, non-modified epoxy
resins, while their toughnesses are better due to the introduction of a two phase structure.14-17
Only those oils of poly-unsaturated fatty acid content, especially soybean or linseed oils that can produce
dense epoxy functionality resins, are capable to produce satisfactory properties.7,18,19 Epoxidized vegetable oils
(EVO) of low oxirane values either are not reactive or impart waxy, non-curing properties to the resin system. In
this research, epoxy resins of epoxidized glycidyl ester (EGS) derived from soybean oils were synthesized and
examined. The goals were to remove as much as possible the plasticizing effect of saturated components, to
further increase the oxirane content, and to minimize viscosity to permit use as an efficient reactive diluent.
We reason that EGS with the addition of a terminal epoxy group (glycidyl), which is readily accessible to
nucleophilic attack, should further support reactivity compared with standard, commercial ESO. The increase
in oxirane content, consequent reduction of the ESO molecular size, and a facilitated removal of the saturated
component should each provide a denser intermolecular crosslinking structure and yield a thermosetting resin
material with improved properties.
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2. Experimental2.1. Materials
Refined, food grade soybean oil was purchased from a local grocery store. ESO was purchased from Union
Carbide Corporation. Epichlorohydrin, methylene chloride, meta-chloroperoxybenzoic acid (MCPBA), sodium
carbonate, sodium bicarbonate, sodium sulfite, and anhydrous sodium sulfate were purchased from Fisher
Scientific. Cetyltriethylammonium bromide (CTEAB), 2-ethyl-4-methylimidazole, and 4-methyl-1,2-
cyclohexanedicarboxylic anhydride (MHHPA) were purchased from Aldrich. Commercial DGEBA was supplied
by Momentive with trade name EPON Resin 828. Mold release agent Chemlease 41-90 EZ was purchased
from Chem-Trend, Inc.
2.2. Soap and free fatty acid preparationSoybean oil derived free fatty acids (FFA) were made via acid neutralization of soap. Vegetable oil was
reacted with sodium hydroxide to generate soap, then acidified with sulfuric acid to pH
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Glycidyl ester (GE) and sodium carbonate were mixed with methylene chloride. MCPBA dissolved in
methylene chloride was added dropwise at a reaction temperature below 15C for 4 hours to complete
epoxidation. The reaction mixture was washed with 10% sodium sulfite and then by 10% sodium bicarbonate
and water. Methylene chloride was removed by in vacuo rotary evaporation and the product EGS was dried
using anhydrous sodium sulfate. Epoxidation also was accomplished by an analogous performic acid process
except using toluene as solvent instead of benzene.20
2.4. CharacterizationInfrared spectra (IR) were conducted on a Nicolet Nexus 470 E.S.P. spectrophotometer.
1H NMR spectra
were obtained on a Varian VXR 400 MHz spectrometer using DMSO-d6 as solvent. Iodine value measurements
were based on ASTM Method D554-95. Oxirane value was measured using AOCS Method Cd 9-57. Viscosity
was tested on a Brookfield LVDV-III+ Ultra Rheometer at 25C.
2.5. Curing reactionThe weight ratios of EGS/ESO to DGEBA resin blend chosen for the present work were 0:100 (pure DGEBA),
10:90, 30:70, 50:50, 70:30; and 90:10. Stoichiometric weight of MHHPA curing agent and 1 wt% (based on
epoxy part) of 2-ethyl-4-methylimidazole were added to the epoxy resin blend. After mixing by a high shear
mixer for 10 min, the mixture was degassed for 30 min, then poured into a mold sprayed with a mold release
agent. Curing was performed at 145o
C for 15 hrs for all blends except ESO-DGEBA (90:10) blend, which was
firstly pre-cured at 145oC for 10 min then mixed again and poured into the mould for fully cure at 155
oC for 15
hrs, because of the low reactivity of ESO. The postcure for all samples were performed at 175oC for 1 hr.
The mixtures weighing 2 to 3 mg encapsulated in aluminum hermetically sealed pan were also cured on a
differential scanning calorimetry machine at a heating rate of 10 oC/min from 40-250 oC to study the cure
behavior of the different formulations.
2.6. Thermal TestsDSC (Q2000, TA Instrument) was used to determine the glass transition temperature (Tg) of cured resin.
Measurement was carried out over a temperature range from -40 to 180 C at a heating rate of 20 C/min.
Samples were first preheated to 180 C and quenched with liquid N2 to remove any thermal history.
TGA (Q50, TA Instrument) was used to determine the thermal stability of cured resin. Measurement was
performed from 30 to 750 C at a heating rate of 10 C/min under an ambient air flow environment.
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2.7. Mechanical TestsThe flexural properties were determined according to the ASTM method D790 on an Instron 4469
universal testing machine. The modulus was determined in a three-point bending mode, with a sample
dimension of 102 mm12.7 mm3.2 mm. The span was 50.8 mm, the crosshead speed was set at 12.7
mm/min.
3. Results and Discussion3.1. Preparation of Epoxidized Glycidyl Ester
Scheme 1. Synthetic route to EGS. (Soybean oil and fatty acids are shown as simplified structures
containing only oleic acid though they also contain saturated and polyunsaturated fatty acids. See the text for
detail.)
Scheme 1 shows the synthetic route to EGS, oleic acid generalizing a soybean fatty acid chain. Preparation
of mixed FFA from triglyceride is straightforward and well-developed. Acetone was used as a low boiling
recoverable solvent to prepare soap and effect low temperature crystallization. A slight excess of NaOH with
higher concentration was desirable when preparing soap from FFA because unsaturated FFAs are prone to
dissolve in acetone rather than react with base and also unsaturated FFA soap is more soluble in water.21
Carefully dried and finely powdered soap resulted in greater yields of glycidyl esters of fatty acids.22
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A low solubility of soap in epichlorohydrin suggested a phase transfer catalyst was needed to accelerate
the reaction. With CTEAB catalyst, the consumption of soap was completed within half an hour under reflux
condition. Glycidyl esters can also be prepared directly from FFA in EPCH rich medium, and then subsequently
dehydrohalogenating with alkali, but the yield and purity were lower than the soap process.21
The epoxidation
of glycidyl ester of soybean oil (GES) was carried out using MCPBA or in situ generated performic acid. The
former was more efficient, however, due to the low solubility of MCPBA in methylene chloride, large amounts
of recoverable solvent was required for the epoxidation.
Figure 1. IR spectra of soybean oil, mixed-FFA, GES and EGS
Figure 1 shows the FT-IR spectra of soybean oil, mixed FFA, GES and EGS. The band at 3008 cm-1
was
attributed to the C-H stretching of =CH in unsaturated fatty acid, such as oleic acid, linoleic acid or linolenic acid.
New bands at 910 cm-1 and 852 cm-1in the spectrum of GES, with the disappearance at 937 cm-1 in spectrum of
mixed-FFA means the occurrence of glycidyl group. The conversion of double bonds to epoxy was confirmed by
the disappearance of the 3008 cm-1 band in GES, and the appearance of band at 752 cm-1 in EGS.
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Figure 2. 1H NMR spectrum and structural assignments of FFA, GE and EGS.
Table 1. General physical properties of epoxy resins
Epoxy ResinOxirane oxygen
(g/100g sample)EEW
Viscosity at 25oC
(mPaS)
EGS 10.1 158 70
ESO 6.9 232 430
DGEBA 8.6 186 13000
Figure 2 shows the1H
NMR spectra of mixed-FFA, GES and EGS, where linoleic acid was used as a
generalized compound for structural assignments. The spectra showed no evidence of side reactions in
preparing GES using soap process, nearly quantitative conversion of double bonds to epoxy groups, and no
oxirane ring opening during the epoxidation of GES to EGS using MCPBA, i.e., showed complete conversion but
a lack of side reactions.
General properties of EGS product compared to ESO, ELO, EGL and DGEBA is shown in Table 1.
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3.2. Viscosity reducing ability
Figure 3. Viscosity of DGEBA with various EGS/ESO concentrations.
It was found that EGS had inherently lower viscosity than ESO. EGS has an extra glycidyl group and lower
molecular weight compared to ESO, which is a triglyceride and has oligomeric behavior. The viscosity reducing
abilities of EGS and ESO were tested at different concentrations replacement of DGEBA resin, which has a high
viscosity at 13000 mPaS (see Figure 3). ESO and EGS all showed good miscibility with DGEBA; however, EGS
exhibited a much better viscosity reducing ability than ESO. Only 30 wt% of EGS reduced the DGEBA resin
viscosity to value below 1000 mPaS, which is indispensable for many applications. At least 50 wt% of ESO was
needed to reduce DGEBA resin to the same viscosity.
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3.3. Curing of Reaction
Figure 4. Dynamic thermograms of DGEBA-EGS/ESO-MHHPA systems
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Table 2. DSC results of curing DGEBA-EGS/ESO-MHHPA systems
Composition H, (J/g)*H, (kJ/mol)
Tonset, (
oC) Tpeak,(
oC)
Pure DGEBA 355.3 66.4 133.7 151.910wt% EGS 347.7 63.8 138.0 156.6
30wt% EGS 348.2 61.8 138.1 157.7
50wt% EGS 340.2 58.4 136.9 159.2
70wt% EGS 336.6 55.9 136.5 160.9
90wt% EGS 334.8 53.9 136.7 163.3
Pure EGS 321.5 52.5 141.3 167.6
10wt% ESO 359.9 68.5 134.4 153.9
30wt% ESO 320.6 63.4 135.1 156.0
50wt% ESO 300.2 61.7 140.3 159.8
70wt% ESO 281.4 60.3 143.2 167.8
90wt% ESO 250.1 55.9 147.6 205.4
Pure ESO 230.0 52.6 182.6 215.9
* based on the total number of epoxy groups.
Differential scanning calorimetry was applied to study the curing behavior of the blended epoxy resins, as
shown in Figure 3, the exothermic peaks were characteristic of the epoxy and anhydride curing reactions.
Integration of these peaks allows the determination of the enthalpy of curing reaction(H), onset curing
temperature (Tonset) and exothermic peaks (Tpeak). The results are shown in Table 2.
From Figure 3, the pure DGEBA and ESO all show single exothermic reaction peaks at 152oC and 216
oC,
respectively. The higher Tpeakvalue of ESO means a slower reaction rate, which was also confirmed by a lower
H value in Table 2. A lower oxirane content of ESO and also internal epoxy function groups react sluggishly
with MHHPA curing agent.
The addition of ESO to DGEBA lead to a shifting ofTpeakand Tonset to higher values. With a decrease ofH
value, two partially overlapped peaks were clearly observed, especially for 50 wt% ESO or higher replacement,
which suggested that there are decreasing levels of ESO miscibility in the DGEBA. Non-homogenous mixing will
prevent complete cure of the epoxy resin. ESO has internal, hindered epoxy groups whereas DGEBA has
glycidyl groups of less steric hindrance and more reactive than the internal epoxy groups of ESO. Similar results
have also been reported by Altuna23
and Boquillon.24
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The prepared EGS resin showed a quite different and interesting curing behavior. The neat EGS shows two
overlapped peaks, similar to the blend of DGEBA and ESO, which is believed to be due to the inherent different
reactivity of glycidyl and internal epoxy function groups. The Tpeakand Tonsetvalue of EGS were more than 40oC
lower than ESO, which indicated EGS is much more reactive than ESO. Increased addition of EGS to DGEBA also
lead to shifting ofTpeak to higher values, but the Tonset remained nearly constant, and only a 16oC increase of
Tpeak was observed for 90 wt% EGS replacement compared to pure DGEBA, while it was 54oC for 90 wt% ESO
replacement.
The H (J/g) also followed a similar trend. The higher oxirane content of EGS, which bears glycidyl groups
like DGEBA, appears to facilitate a more homogenous three dimension polymer structure upon curing
compared to ESO blends. One note of interest was that a small amount of replacement, e.g., 30 wt% EGS or
below, or 10 wt% ESO, had little effect on the H or Tpeak values of DGEBA, which may be related to
homogeneity and compatibility with the DGEBA.
3.4. Thermal Properties
Figure 5. The change of glass transition temperatures with various ESO/EGS contents
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The glass transition temperature (Tg) is considered one of the fundamental characteristics as it relates to
polymer properties and processing. For a polymer to serve as a useful plastic, its Tg must be appropriately
higher than the temperature of its intended work environment.25
The aliphatic amine,7,26
or boron trifluoride
diethyl etherate27,28
cured ESO polymers generally have very low Tg (even below 0oC). Aromatic amine
29,
cycloaliphatic amine,2thermal latent initiator30 or anhydride31 cured ESO polymers generally have higher Tg, but
it is still rare to see a cured ESO6with Tg above 60
oC. Low Tg represents a low crosslink density, as mentioned
above. Due to the low oxirane content of ESO, sluggish reactivity of internal epoxy groups with nucleophilic
curing agents, the self intermolecular crosslinking of ESO, and unreactive saturated components like stearic
acid, palmitic acid or myristic acid that act as plasticizers, which further decrease the polymer Tg.
DSC and Dynamic Mechanical Analysis (DMA) are widely used to characterize the Tg. It is necessary to note
here that for most thermosetting plastics, the DMA measurement based on the tan peak at a frequency of 1
Hz generally occurs at a temperature as much as 15-20
o
C above Tg as measured by dilatometry or DSC.
32
Thechange of cured epoxy resin Tg as measured by DSC is shown in Figure 5.
Not surprisingly, the MHHPA cured pure EGS had a much higher Tgat 88oC, which was nearly 40
oC higher
than ESO though still lower than the pure DGEBA resin.
Addition of ESO or EGS lead to a decrease ofTg,for smaller replacement, e.g., below 30 wt%, the Tg values
of ESO-DGEBA or EGS-DGEBA systems were quite similar, which indicated the Tg behavior was mainly
determined by the DGEBA structure. Further increase the replacement contents of ESO or EGS, theTg values
decreased rapidly, especially for the ESO system. The inherent aliphatic long chain structure of ESO and the
higher saturated content and lower epoxy groups make it difficult to produce a densely crosslinked structured
polymer as some segments will vibrate more freely upon thermal stress.12
It was also found that neat ESO or higher replacement (above 50 wt%) of ESO-DGEBA thermosetting
polymer showed a broad transition from the glassy to the rubbery state. Similar behavior was also found in
ELO replacement of di-glycidyl ether of bisphenol F (DGEBF) resin,33
which was not found in EGS-DGEBA system.
The plasticizing effect of saturated fatty acids in the network32and/or the different reactivity of ESO and DGEBA
lead a broad distribution of polymer molecular weight and indicat a heterogeneous polymer network was
formed.34
Figure 6 presents the TGA curves as a function of temperature for the cured epoxy resin. Since ESO-
DGEBA resin had similar thermal stability with EGS-DGEBA resin, only the latter is shown here. TGA results
indicated all cured EGS-DGEBA resins appear thermally stable to temperatures below 300 oC. Addition of EGS
lead to an earlier onset of degradation. All the resins similarly presented two stage degradation behavior. The
first stage of decomposition, from 350 to 450oC, is believed to be due to the pyrolysis of the crosslinked epoxy
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resin network, decomposition of unreacted MHHPA, and dehydration of hydroxyl groups. The second loss
stage from ~450 to 600 oC was considered to be the complete decomposition of the smaller fragments like
cyclized or aromatic degradation byproducts as indicated by a decrease of char residue when EGS component
was increased in DGEBA.
Figure 6. TGA analysis of cured EGS-DGEBA blends compared to pure EGS and pure DGEBA.
3.5. Mechanical PerformanceThe flexural properties of the cured resin system with varying ESO/EGS content were determined and the
results were listed in Table 3. As can be seen from Table 3, 10 wt% of ESO or EGS replacement of DGEBA lead
to an improvement in flexural modulus, although further increases of ESO/EGS content lead to a decrease of
flexural modulus. Similar results were also reported in an amine cured soy-based epoxy resin system.34
The
flexural stress of EGS-DGEBA exhibited a gradual decrease until 50 wt%, then followed an abrupt degradation.
While for ESO-DGEBA, such degradation occurs at 30 wt%.
As discussed previously, two overlapping peaks in the curing curves determined by DSC were observed
when high contents of EGS/ESO were added into DGEBA. Different reactivity or reduced compatibility of
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ESO/EGS with DGEBA, may ultimately prevent the ESO/EGS resin from fully participating in the crosslinking.
Therefore, the resulting crosslinked thermosets may become increasingly plasticized by partially reacted
ESO/EGS resins at high contents, leading to a decrease of flexural strength. EGS has higher oxirane value and
was observed to be more reactive with DGEBA compared to ESO, so a higher content of EGS replacement of
DGEBA was achieved with less degradation of the mechanical strength. Due to the inherent lower epoxy
content and sluggish reactivity of internal epoxy function groups, a lower ESO content replacement was
required to prevent additional sacrifice of mechanical performance.
Table 3. Flexural properties of cured DGEBA-EGS/ESO resin
Composition Flexural StrengthMPa Flexural ModulusMPa
Pure DGEBA 138.1 2945.0
10wt% EGS 133.0 3162.130wt% EGS 125.2 2837.8
50wt% EGS 121.9 2829.1
70wt% EGS 91.0 2608.2
90wt% EGS 81.3 1687.6
10wt% ESO 124.2 2977.2
30wt% ESO 120.8 2822.8
50wt% ESO 107.0 2471.0
70wt% ESO 81.4 2270.8
90wt% ESO 60.0 1652.8
4. ConclusionEGS resin materials were produced from soybean oils with reduced saturated FFA fraction content. The
products were characterized and showed high oxirane contents and were more reactive than ESO. The EGS
blends were cured by MHHPA and their thermosetting polymer Tgs measured in comparison to control ESO
cured in similar fashion. The EGS resin systems had significantly reduced viscosity compared to their pure
DGEBA or ESO-blend epoxy counterparts. The products displayed glass transitions that were a fairly simple
function of oxirane content with some added influence of glycidyl versus internal oxirane reactivity. The
products displayed improved Tgs and mechanical properties compared to their ESO counterparts and, in
addition to an inherently low viscosity and efficient viscosity reduction, should therefore be more attractive as
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a reactive diluent. For instance, EGS derived from renewable sources could further enable defect-free
fabrication of complex, shaped epoxy composites for structural composite applications.
5. References1 Mark, H. F., Ed. Encyclopedia of Polymer Science and Technology, Wiley-Interscience: New York, 2004.
2 Czub, P., Macromolecular Symposia242, 60 2006.
3 Varley, R. J.; Tian, W., Polymer International53, 69 2004.
4 Raquez, J. M.; Delglise, M.; Lacrampe, M. F.; Krawczak, P., Progress in Polymer Science35, 487 2010.
5 Cheng, X.; Chen, Y.-X.; Du, Z.-L.; Zhu, P.-X.; Wu, D.-C., Journal of Applied Polymer Science119, 3504 2011.
6 Tan, S. G.; Chow, W. S., Polymer-Plastics Technology and Engineering49, 1581 2010.
7 Xua, J. X.; Liu, Z. L.; Erhan, S. Z., Journal of the American Oil Chemists' Society81, 813 2004.
8 May, C. A., Ed. Epoxy Resins Chemistry and Technology, Marcel Dekker, Inc.: New York, 1988.
9 Raghavachar, R.; Sarnecki, G.; Baghdachi, J.; Massingill, J., Journal of Coatings Technology72, 125 2000.
10 Chandrashekhara, K.; Sundararaman, S.; Flanigan, V.; Kapila, S., Materials Science and Engineering: A412, 2 2005.11 Gupta, A. P.; Ahmad, S.; Dev, A., Polymer Engineering & Science51, 1087 2011.
12 Gelb, L.; Ault, W.; Palm, W.; Witnauer, L.; Port, W., Journal of the American Oil Chemists' Society37, 81 1960.
13 Czub, P., Macromolecular Symposia245-246, 533 2006.
14 Kar, S.; Banthia, A. K., Materials and Manufacturing Processes19, 459 2004.
15 Miyagawa, H.; Misra, M.; Drzal, L. T.; Mohanty, A. K., Polymer Engineering & Science45, 487
2005.
16 Jin, F.-L.; Park, S.-J., Materials Science and Engineering: A478, 402 2008.
17 Tan, S. G.; Chow, W. S., J Therm Anal Calorim101, 1051 2010.
18 La Scala, J.; Wool, R. P., Polymer46, 61 2005.
19 Meier, M. A. R.; Metzger, J. O.; Schubert, U. S., Chemical Society Reviews36, 1788 2007.
20 Gan, L. H.; Ooi, K. S.; Goh, S. H.; Chee, K. K., Journal of Applied Polymer Science46, 329 1992.
21 Maerker, G.; Saggese, E.; Port, W., Journal of the American Oil Chemists' Society38, 194 1961.
22 Kester, E. B.; Gaiser, C. J.; Lazar, M. E., The Journal of Organic Chemistry08, 550 1943.
23 Altuna, F. I.; Espsito, L. H.; Ruseckaite, R. A.; Stefani, P. M., Journal of Applied Polymer Science120, 789 2011.
24 Boquillon, N.; Fringant, C., Polymer41, 8603 2000.
25 Stevens, M. P., Polymer Chemistry : An Introduction; Oxford University Press 1999.
26 Lu, P.; University of Missouri-Rolla, Rolla: 2001.
27 Liu, Z.; Doll, K. M.; Holser, R. A., Green Chemistry11, 1774 2009.
28 Liu, Z.; Erhan, S. Z., Journal of the American Oil Chemists' Society87, 437 2009.
29 Earls, J. D.; White, J. E.; Lpez, L. C.; Lysenko, Z.; Dettloff, M. L.; Null, M. J., Polymer48, 712 2007.
30 Park, S.-J.; Jin, F.-L.; Lee, J.-R., Macromolecular Rapid Communications25, 724 2004.
31 Gerbase, A.; Petzhold, C.; Costa, A., Journal of the American Oil Chemists' Society79, 797 2002.
32 Tanrattanakul, V.; Saithai, P., Journal of Applied Polymer Science114, 3057 2009.
33 Miyagawa, H.; Mohanty, A. K.; Misra, M.; Drzal, L. T., Macromolecular Materials and Engineering289, 629 2004.
34 Miyagawa, H.; Misra, M.; Drzal, L. T.; Mohanty, A. K., Journal of Polymers and the Environment13, 87 2005.
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