Investigations of the morphology of various epoxy-based nanocomposites

Goal of present paper is to assess the applicability of common interphase models on thermoset polymers like epoxy resin. Abstract theoretical constructs like the multi-core-model, the interphase volume model or the interphase power law are examined in order to determine their physical applicability. Samples used were bisphenol-A type epoxy resin with anhydrite hardener and AlN, Al₂O₃, MgO and SiO₂ filler of nanometric dimensions. The samples have previously been examined in terms of their dielectric and thermal properties. Now thermogravimetric analysis and differential scanning calorimetry is utilized in order to assess the structural changes of the polymer. The composites showed consistently higher char content than the base resin would suggest. This additional char could be interpreted as rigid polymer layer that adheres to the particle surfaces, however, differential scanning calorimetry does not support this theory. Primarily, MgO filled samples showed distinct behavior, with significantly reduced TG, as well as a narrower peak than all other investigated materials.