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

Butadiene-acrylonitrile random copolymers with various molecular weigh ts and end-groups were introduced into a system consisting of the digl ycidyl ether of bisphenol A (DGEBA) and 3,3'-dimethyl-4,4'-diamino dic yclohexyl methane (3DCM) cured at 50-degrees-C. We studied the influen ce of a low level of soluble additive on the polymerization rate, evol ution of viscosity, gelation and vitrification times, and the final ne twork in the cases of different additive molecular weight and end grou ps of the additive. It was found that the additive influences the fina l network only by dissolving in the matrix and that the dilution effec t plays a minor role, but the catalytic effect of an additive can play a significant role on the polymerization depending on the additive en d groups. However, in all the rubber-modified systems, the phase separ ation has no direct influence on the polymerization rate and the chang e of viscosity.