Thermal and electrical behaviour of epoxy-based microcomposites filled with Al2O3 and SiO2 particles

Epoxy resin is a polar thermosetting polymer that is widely employed in different branches of industry and everyday life, due to their stable physical and chemical properties. Of all the polymer materials currently being used in the electrical insulation industry, epoxy resin is the most widely used kind, together with polyethylene and chosen as the base polymer material in the present study. As a common practice, in order to obtain materials of the desired thermal, mechanical and electrical properties, polymers are processed with different types of inorganic fillers. In this paper, the authors made an attempt to thoroughly analyze both the thermal and the electrical behaviour of the created epoxy microcomposites. Epoxy-based composites containing microparticles of aluminum oxide and silicon dioxide were prepared by high shear mechanical mixing and ultrasonic processing to obtain a fine dispersion of the fillers in the matrix. The incorporation of all filler types led to noticeable improvement in thermal conductivity compared to the pure epoxy resin. The thermal conductivity and the relative permittivity of the composites were greatly influenced by the filler loading of the inorganic particles. Rules of mixture are used to predict the thermal conductivity and the relative permittivity of two-phase composites have been applied to compare experimental results with theoretical models.