Experimental and Modeling Study of Interfacial Polarization (MWS) in a Two-Phase Model Epoxy Solid System

A two-phase epoxy-amine network was synthesized by dispersing spherical cross-linked epoxy microgels into a chemically similar epoxy-amine matrix, introducing a controlled topological contrast in cross-link density while maintaining high interfacial compatibility. Dielectric spectroscopy was used to investigate dielectric relaxations and Maxwell–Wagner−Sillars (MWS) polarization in this two-phase system. The electrical properties of each phase were independently determined and used as inputs for the Maxwell–Wagner model of interfacial polarization that explicitly accounted for the frequency-dependent behavior of both components. Excellent agreement between experimental results and theoretical predictions confirmed that solid polymer mixtures follow the classical Maxwell–Wagner model. The relaxation times associated with interfacial polarization followed the thermal behavior of the matrix’s DC conductivity, suggesting a shared activation mechanism. This agreement enabled the investigation, through the model, of general trends governing this polarization mode. Investigating this polarization mode by dielectric spectroscopy is a powerful tool to describe interfaces and their possible evolution under different stimuli.