The influence of processing parameters on interphase morphology in polymer composites based on phase-separating thermoplast/epoxy blends

In this study the occurrence of interfacial phase separation in fibre-reinforced composites has been investigated using phase-separating polystyrene/epoxy and polystyrene/poly(phenylene ether)/epoxy blends as a matrix system. The influence of surface tension and polarity of the different constituents, viscosity of the blend and reaction rate of the epoxy resin, on the resulting morphology of the interfacial epoxy phase formed during cure, have been studied. Morphological studies on short-fibre-reinforced composites showed that increasing fibre surface tension results in a decreasing contact angle of the interfacial epoxy phase on the fibre. Lowering viscosity results in an increased wetting of the fibres by the epoxy phase. In the temperature range studied, the viscosity rather than the epoxy reaction rate determines the morphology of the epoxy interphase.