A nonisothermal differential scanning calorimetry study of the curing kinetics of an unsaturated polyester system

Ng, Hendra; Manas‐Zloczower, Ica

doi:10.1002/pen.760291604

Cited by 74 publications

(17 citation statements)

References 20 publications

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“…The values of heat evolved during the curing are smaller than those reported in the literature [12,13] which are reported to be in the region of 292.6 to 426 J/g. This difference can be attributed to the different types of unsaturated polyesters used.…”

Section: Resultscontrasting

confidence: 71%

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

et al. 2001

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Unsaturated polyesters are synthesized by means of polyesteri®cation, often with catalysts like strong acids, metal oxides and metal-organic salts. Most often, the catalysts used cannot be separated from the bulk of the polyester. Also, some organic or inorganic additives ± called ®llers ± which are used with the polyester in order to decrease cost, affect the curing of the polyester. In this work the effect of residual catalyst on the curing of unsaturated polyester is studied. Unsaturated polyesters were prepared using propylene glycol with a 10% molar excess over stoichiometry and a mixture of dicarboxylic acids, namely maleic acid (unsaturated) adipic acid (saturated) and phthalic anhydride (saturated) at a molar ratio 1:2:2. Lead dioxide, p-toluenesulfonic acid and zinc acetate were used as catalysts, at 0.1% w/w. After the polyesteri®cation, the polymers were diluted with styrene at a proportion of 100:30 w/w. The resins were cured by using MEKP (methylethylketone peroxide) as initiator and CoNp (cobalt naphthenate) as accelerator. Catalysts affect the ®nal color of the polyester. The kinetics of curing of the resins was studied by DSC analysis based on the exothermic peak due to the double bonds breaking to give crosslinked macromolecules. The heat released ÁH is decreased by the presence of catalyst, while activation energy, the frequency factor and the order of reaction are increased.

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Section: Resultscontrasting

confidence: 71%

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

et al. 2001

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“…Other researchers [47,48] have reported a range of reaction heat from 292.6 to 426 J/g for UP resins. The existence of this wide range may be because of the different types of UP resins and free radical initiator systems employed in each study [35].…”

Section: Resultsmentioning

confidence: 99%

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Martin

2006

Polymer Engineering & Sci

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The curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate as promoter is studied by DSC at different heating rates. A high promoter/peroxide ratio is used. The DSC curves show two exothermic peaks. It has been assumed that they represent two independent cure reactions. A set of kinetic parameters for each DSC peak has been obtained. They describe the overall cure process using an empirical kinetic model. Nth order and autocatalytic kinetic functions have been employed. A computer program was developed to calculate the degrees of conversion associated with each peak, and to evaluate the kinetic parameters. The calculation algorithm uses the Runge-Kutta numerical integration and the ' 'downhill simplex method.' ' This methodology permits to find all kinetic parameters simultaneously. DSC experimental data are very well fitted. The simulated first peak occurs always before the second one, and the fraction of reaction heat associated with the first peak over the overall reaction heat decreases with heating rate. Moreover, activation energies are in good agreement with the tabulated values for typical free radical polymerization induced by thermal and redox decomposition of the peroxides. POLYM. ENG. SCI., 47:62-70, 2007.

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“…The mathematical modeling of the curing of thermoset resins has been studied in the recent years [15–19]. UP resins with promoter exhibit two exothermic differential scanning calorimetry (DSC) peaks, whereas the resins without promoter show only a single exothermic DSC peak [20, 21].…”

Section: Introductionmentioning

confidence: 99%

Kinetic modeling of nanoclay‐reinforced unsaturated polyester resin

2011

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Curing behavior of an unsaturated polyester (UP) resin containing 1 wt% organically modified clay (OMC) catalyzed with methyl ethyl ketone peroxide (MEKP) initiator and promoted by cobalt naphthenate accelerator was investigated by dynamic differential scanning calorimetry (DSC) at five different heating rates of 5, 10, 15, 20, and 25°C/min. X‐ray diffraction and transmission electron microscopy were used to evaluate the morphology of UP/OMC composites. Results showed a mixture of intercalated and exfoliated morphology. The dynamic DSC curing curves showed a bimodal exothermic peak; therefore, two independent reactions, namely, redox and thermal copolymerizations were assumed. Kinetic parameters were calculated by using autocatalytic model and using Down hill simplex method and Runge–Kutta algorithm for each reaction. The addition of nanoclay resulted in decrease of the activation energy of the redox reaction compared to that of the neat UP resin. Also, the pre‐exponential factor of the first reaction for UP/OMC was less than that of the neat UP. Two factors including decreasing the activation energy and decreasing the number ofcollisions of reactionary components finally resulted in increasing the reaction rate of the first reaction out of the whole reaction in the system containing nanoclay compared to the neat UP resin. It is interesting that nanoclay has no effect on the thermal decomposition reaction. POLYM. COMPOS., © 2011 Society of Plastics Engineers.

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A nonisothermal differential scanning calorimetry study of the curing kinetics of an unsaturated polyester system

Cited by 74 publications

References 20 publications

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Kinetic modeling of nanoclay‐reinforced unsaturated polyester resin

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