Electrical performance of silicone rubber / SiO2 nanocomposites under low temperature

This paper investigated the electrical tree growth process in SiR/SiO₂ nanocomposites under the condition of low temperature. Samples were prepared by mixing nano-SiO₂ into room temperature vulcanizing silicone rubber, with the content of 0, 0.5, 1, 1.5 and 2 wt% respectively. The experiment temperature ranged from - 30 °C to -90 °C. AC voltage with a frequency of 50 Hz was applied between a pair of needle-plate electrodes to investigate the electrical tree at different temperatures. The experimental results reveal that both nanoparticles and low temperature environment have a significant impact on the electrical tree growth characteristics of SiR/SiO₂ composites. This paper studied electrical tree growth characteristics from the aspects such as the patterns of electrical tree, fractal dimension and the proportion of cumulative damage. It is suggested that there are both branch tree and bush tree when the temperature is -30 °C or -60 °C, but only pine tree when the temperature is -90 °C. It is also found that tree structure is closely related to the crystalline state.