KINETICS OF THERMOSET CURE AND POLYMERIZATION IN THE GLASS-TRANSITION REGION

A theoretical approach to thermoset cure kinetics based on Arrhenius kinetics and mobility was developed by considering the activation of the reacting group and chain mobility as elementary steps for reaction. This extended kinetic equation was successfully applied to the curing of an epoxy by an amine, the trimerization of a cyanate, and to the polymerization of methyl methacrylate. Full agreement between theory and experimental data was obtained in all cases. The activation energies for chain mobility were exceptionally low (0.3-1 kJ/mol for bisphenol-A-based epoxy and cyanate) which indicates that the structural units must undergo only small-angle rotational oscillations to allow a reaction. A theoretical time-temperature-transformation (TTT) diagram is also presented.