Comparison of the Dielectric Response of Alumina-epoxy Composites with Nano- and Conventional Sized Filler

This paper looks at the differences in dielectric response between epoxy resin composites with conventional and nanoscale alumina filler. Host material, namely bisphenol-A epoxy resin, is the same for all samples. Preparation of the samples is described in detail. Both filler types are treated in similar fashion to ensure comparability of the results. An even distribution of the alumina in case of the nanoscale filler was validated by means of transmission electron microscopy. It is shown by means of dielectric spectroscopy how the particle size and preparation influence the material properties. Measurements were performed in a broad frequency range between 0.01 and 10 MHz, for temperatures between -20C and the glass transition temperature of the host material close to 120C. Possible explanations for the witnessed behavior are presented and the contributing factors discussed.