SINGLE-PHASE AND MULTIPLE-PHASE THERMOPLASTIC THERMOSET POLYBLENDS .1. KINETICS AND MECHANISMS OF PHENOXY EPOXY BLENDS

Abstract

The kinetics of the curing reaction for phenoxy/epoxy/diaminodiphenyl sulfone blends with and without an accelerator have been investigated through differential scanning calorimetry (d.s.c.), FTi.r. and viscosity measurements. Phenoxy is miscible with epoxy monomer and low-molecular-weight epoxy during the early stages of curing, but phase separation starts when the epoxy molecular weight is increased to a critical value. The viscosity and the crosslinking density increase with increasing epoxy molecular weight. The viscosity at the initiation of phase separation is the most important factor in determining the final morphological structure. Opaque, translucent and transparent products can be obtained by kinetic control of the curing rate. A model to describe the phase separation of any thermoplastic/thermoset blend system in terms of thermodynamics and kinetics is presented in this paper.