STUDIES ON THE PHASE-SEPARATION OF POLYETHERIMIDE-MODIFIED EPOXY-RESIN .1. EFFECT OF CURING RATE ON THE PHASE-STRUCTURE

The effect of the curing rate on the phase structure of a new polyethe rimide-modified epoxy systems was studied. Through changing cure agent s and cure temperature, selecting different molecular weights and end groups of the polyetherimide (PEI) polymers, the curing rates, the pha se separation processes and the morphology of the cured blends were ob served employing differential scanning calorimetry, time-resolved ligh t scattering and scanning electron microscopy. The highly active cure agent 4,4'-oxydianiline leads to phase separation in the early stage o f spinodal decomposition and to a co-continuous phase structure. As to the 4,4'-diaminodiphenyl sulfone cured systems, not only the curing r ate, but the mobility of the PEI molecule also affected the final morp hology of the PEI-modified epoxy resin.