CURE KINETICS OF ELEMENTARY REACTIONS OF A DIGLYCIDYL ETHER OF BISPHENOL-A DIAMINODIPHENYLSULFONE EPOXY-RESIN .2. CONVERSION VERSUS TIME

The kinetics of the elementary reactions (primary amine-epoxy and secondary amine-epoxy) in addition to the overall reaction have been studied in a diglycidyl ether of bisphenol A (DGEBA) epoxy resin system, cured with diaminodiphenylsulfone (DDS) hardener. The conversion versus time data for the elementary reactions and for the overall reaction were obtained by monitoring the changes in concentration of epoxy, primary and secondary amine groups during cure using near-infra-red spectroscopy. The data were evaluated using nth-order and autocatalytic kinetic models. The primary amine-epoxy reaction (linear polymerization) was described well by the nth-order kinetic model over the whole range of conversion of the primary amine, whereas the secondary amine-epoxy reaction was described by both the nth-order kinetic and first-order autocatalytic models in the ranges of initial 30% conversion at 130-degrees-C cure, and 80% conversion at 205-degrees-C cure. The kinetic parameters for each reaction were also obtained. The reactivity ratio of the secondary amine to the primary amine for a non-catalysed reaction increased with increasing cure temperature, whereas the opposite trend was observed for the autocatalysed reaction.