Dielectric properties analysis of silicone rubber

Dielectric properties of silica filled silicone rubber used for high voltage insulation are studied as a function of frequency (1 mHz - 1 MHz) and temperature 213K - 433K.. Two different polarization mechanisms are identified. The frequency dependence of the dielectric constant and loss factor is well characterised by the Havriliak-Negami model. A low interfacial polarization appears in the loss factor ε" but dc conduction dominates at low frequencies thus increasing ε" for all temperatures. From the Havriliak-Negami model, the activation energy of about 0.43 eV is obtained and α-relaxation is identified in the loss factor response at low temperature. Dielectric response behaviour dominated by the hopping charge transport is identified at moderate higher fields.