Abstract: Phenolphthalein poly (ether ether sulphone)(PES-C) was found to be miscible with uncured bisphenol-A-type epoxy resin, i.e., diglyeidyl ether of bisphenol A(DGEBA),as shown by the existence of a single glass transition temperature within the whole composition range. Miscibility between PES-C and DGEBA is considered to be due mainly to entropy contribution. However, dynamic mechanical analysis (DMA) and scanning electron microscopy(SEM) studies revealed that the overall compatibility and the resulting morphology of the cured blends are dependent on the curing agent. For the blends cured with amines (4,4'-diamino diphenyl methane, 4,4'-diamino diphenyl sulfone), no phase separation occurs as indicated by either DMA or SEM. However, for the blends cured with anhydrides (maleic anhydride, phthalic anhydride), both DMA and SEM clearly show the phase separation. The differences in the overall compatibility and the resulting morphology between the aminecured and anhydride-cured systems have been discussed in terms of thermodynamics and kinetics.

Key words: epoxy resin, phenolphthalein poly(ether ether sulphone), blend, compatibility