PROPERTIES OF INTERPENETRATING POLYMER NETWORKS OF EPOXY-RESIN POLYBISMALEIMIDE SYSTEMS

Polymer blends were prepared from epoxy resin and bismaleimide (BMI), which form polymer networks, via different reaction mechanisms. Influences of concentration of BMI on dynamic mechanical, tensile, and thermal degradation properties were examined for these blends. The rubbery modulus and primary dispersion temperature (T(a)) considerably increased with increasing BMI component. The modulus behavior in the rubbery state followed Budiansky's equation and suggested the formation of Interpenetrating Polymer Networks (IPN). T(a) followed the T(g) prediction for copolymers, indicating a profound molecular mixing between the two components, The activation energy (DELTA-E) for the primary dispersion was determined from the temperature dependence of shift factor. Increase in DELTA-E with BMI component indicated that the segmental motion became more restricted. The effects of IPN formation brought about tensile strengths at high temperature which were considerably larger than those of the component networks at 25 approximately 50 wt% of BMI and also improved the thermal resistance.