Temperature dependence of dielectric breakdown of silicone-based dielectric elastomers

A large number of insulation/dielectric failures in power systems are related to thermally-induced dielectrical breakdown, also known as ‘thermal breakdown’, at higher operating temperatures. In this work, the thermal breakdown behavior of typical silicone formulations, used as dielectrics in stretchable electronic devices, is analyzed at practically relevant operating temperatures ranging from 20°C to 80°C. An effective way of delaying the thermal breakdown of insulating materials is to blend micro- or nano-sized inorganic particles with high thermal conductivity, to dissipate better any losses generated during energy transduction. Therefore, two types of commercial silicone formulations, blended with two types of rutile hydrophobic, high-dielectric TiO₂ fillers, are investigated in relation to their dielectric properties, namely, relative permittivity, the dissipation factor, and electrical breakdown strength. The breakdown strengths of these silicone composites are subsequently evaluated using Weibull analysis, which indicates a negative correlation between temperature and shape parameter for all compositions, thus illustrating that the homogeneity of the samples decreases in line with temperature, but the breakdown strengths nevertheless increase initially due to the trapping effect from the high-permittivity fillers.