Dielectric properties of cured epoxy resin + poly(ethylene oxide) blends

Epoxy resin (ER) + poly(ethylene oxide) (PEO) blends cured with 4,4′-diaminodiphenyl-methane were studied by thermally stimulated currents and dielectric relaxation spectroscopy. The results confirm components miscibility with dielectric glass transition temperature-composition dependence obeying the empirical Gordon–Taylor G–T equation with k = 0.38. Positive departures from the G–T curve appear at high PEO loadings due to crystallization of the linear polyether. Subtle perturbations of the local-chain relaxation dynamics and the relatively low k estimate advocate for weakened intermolecular-specific interactions in the miscible blends, compared with the intramolecular self-association of hydroxyls in pure ER, suggesting structural similarity as the primary driving force for phase miscibility.