Synthesis and Kinetics Study of Vinyl Ester Resin in the Presence of Triethylamine

The synthesis of an epoxy vinyl ester resin was carried out using a bisphenol-A based epoxy resin and methacrylic acid in the presence of triethylamine as a catalyst. The reaction was performed in the temperature range of 90-120oC and epoxy to carboxyl group ratio of 1. In all conditions a conversion of more than 95% was achieved. The reaction time (for conversions more than 95%) was different from 1.5 h at 120oC to more than 8 h at 90oC. The results indicated that reaction followed a first-order kinetics. The order of reaction with respect to methacrylic acid was also investigated by using excess method. It was found that in the reaction conditions, the reaction rate was independent of carboxyl group concentration. The specific rate constant, calculated by the regression analysis, was found to obey Arrhenius expression. The activation energy and frequency factor were found to be 82.61 kJ/mol and 5.43×109 min-1, respectively. FTIR Analysis of vinyl ester resin revealed that addition esterification reaction between carboxyl and epoxy groups took place and no side reactions (i.e., etherification reaction between epoxy and hydroxyl groups) occurred during the synthesis.