RUBBER-MODIFIED EPOXIES .1. INFLUENCE OF PRESENCE OF A LOW-LEVEL OF RUBBER ON THE POLYMERIZATION

Butadiene-acrylonitrile random copolymers with various molecular weights and end-groups were introduced into a system consisting of the diglycidyl ether of bisphenol A (DGEBA) and 3,3'-dimethyl-4,4'-diamino dicyclohexyl methane (3DCM) cured at 50-degrees-C. We studied the influence of a low level of soluble additive on the polymerization rate, evolution of viscosity, gelation and vitrification times, and the final network in the cases of different additive molecular weight and end groups of the additive. It was found that the additive influences the final network only by dissolving in the matrix and that the dilution effect plays a minor role, but the catalytic effect of an additive can play a significant role on the polymerization depending on the additive end groups. However, in all the rubber-modified systems, the phase separation has no direct influence on the polymerization rate and the change of viscosity.