Effects of nano filler on treeing phenomena of silicone rubber nanocomposites

Polymer nanocomposite has recently drawn considerable attention because nanocomposites or nanostructured polymers have the potential of improving the electrical, mechanical, and thermal properties as compared to the neat polymers [1]. In this paper, the polymer nanocomposite was made by the mixed addition of SiO2 nanoparticle with the radio of 20 nm into room temperature vulcanized (RTV) silicone rubber (SiR), with the filler content from 0 to 5 wt% respectively. The typical needle-plate electrode was employed to investigate the relationship between electrical tree propagation characteristics and the content of nano filler with the ac voltage of 50 Hz. Both the structures and growth characteristics of electrical tree in SiR were observed by using a digital camera and a microscope system. Obtained results show that the distribution of tree structures is different between base SiR and its nanocomposites specimens. The growth speed varies a lot with the content of nano fillers, and there is an obvious improvement in tree initiation time as the increase of filler content. The possible reasons for the improvement in electrical tree growth and initiation time with the addition of nano fillers are discussed.