RUBBER-MODIFIED EPOXIES .3. ANALYSIS OF EXPERIMENTAL TRENDS THROUGH A PHASE-SEPARATION MODEL

A phase separation model was used to simulate the morphologies obtained in a system consisting of a diepoxide based on bisphenol-A diglycidylether cured with a cycloaliphatic diamine, in the presence of an epoxy-terminated butadiene-acrylonitrile random copolymer (ETBN). A detailed analysis of experimental factors affecting resulting morphologies was previously reported. The model, based on a thermodynamic description through a Flory-Huggins equation, and constitutive equations for polymerization and phase separation rates, could explain most of the observed trends. A nucleation-growth mechanism was believed to take place because of the very low values of interfacial tensions for this type of systems. Conditions which would lead to spinodal demixing are also discussed.