Optoelectrical properties of epoxy/silica nanocomposites

Nanosilica/epoxy composites were prepared with different silica concentrations (0, 3, 5, 10 and 15 wt-%). The optical and electrical properties of the prepared composites were investigated as a function of filler content, temperature and applied electric field frequency. The obtained optical data were analysed in terms of absorption formula for non-crystalline materials. Both the optical energy gaps and the width of the energy tails of the localised states have exhibited silica concentration dependence. It has been observed that electrical quantities such as the AC conductivity, measured using the impedance spectroscopy and the dielectric constants, vary with the applied frequency, silica concentrations and temperature. In addition, the relaxation time and activation energy for the thermal conduction processes were calculated and reported.