Dielectric studies of phase separation induced by chemical reaction in thermoplastic modified epoxy

Abstract Dielectric measurements were performed in real time to follow the reaction 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 types of morphology, made of a TP‐rich phase and an EA‐rich phase. In an electrically stimulated sample, the phase separation results in an interfacial polarization seen by dielectric spectroscopy. This paper shows the possibility of monitoring both the phase separation and the vitrification of each phase. The gelation of the resin is not detected by this technique. By correlating morphological observations with characteristic dielectric responses, the type of morphology can be identified from the permittivity during the phase separation.