DIELECTRIC STUDIES OF PHASE-SEPARATION INDUCED BY CHEMICAL-REACTION IN THERMOPLASTIC MODIFIED EPOXY

Dielectric measurements were performed in real time to follow the reac tion of polymerization in thermoplastic (TP) modified epoxy-amine (EA) blends. This epoxy system exhibits a phase separation induced by the reaction in the liquid stage of the resin. It results in 3 different t ypes of morphology, made of a TP-rich phase and an EA-rich phase. In a n electrically stimulated sample, the phase separation results in an i nterfacial polarization seen by dielectric spectroscopy. This paper sh ows the possibility of monitoring both the phase separation and the vi trification of each phase. The gelation of the resin is not detected b y this technique. By correlating morphological observations with chara cteristic dielectric responses, the type of morphology can be identifi ed from the permittivity during the phase separation.