Study of curing of epoxy resins by acid anhydrides using differential scanning calorimetry

Course and kinetics of the curing of epoxy resins by acid anhydrides were studied by differential scanning calorimetry (DSC). The heat of reaction at 107.5°C was found to lie between ?302.2to ?333.2 J/g (?72.2 to ?79.6 cal/g), depending on the composition of the reaction system. For one reaction system measurements were made at three different temperatures. From DSC data the reaction order and rate constants were evaluated. Between 18 to 80% conversion the curing reaction was found to be 0.5 order, and from 80 to 98% conversion to be first order. From the rate constants using the Arrhenius equation the activation energy was calculated. The values of the activation energy are 58.2 KJ/mol (13.9 kcal/mol) for 0.5 order and 56.1 KJ/mol (13.4 kcal/mol) for first order reaction.