The effect of nano SiO2 additive on electrical tree characteristics in epoxy resin

Electrical tree is an electrical aging phenomenon which seriously destroys polymer insulation. The addition of nano particle can improve the dielectric properties of polymer, and it is also expected to play a role in inhibiting electrical tree. In the current paper, the SiO₂ nanoparticles uniformly dispersed into the epoxy resin, and the electrical tree in nanocomposite containing up to 5 wt% nano SiO₂ was observed clearly. Under the voltage of 18kV, the effect of nano SiO₂ fillers on the initiation and growth of electrical tree in epoxy nanocomposite were studied. It was found that the initiated rate of electrical tree could reduce with the increase of nano filler content, and the electrical tree shape would gradually become from branch in pure epoxy resin to jungle in 5 wt% SiO₂/EP nanocomposite, the growth rate of electrical tree would also slowed sharply. This proved that nanoparticles´ addition changes the growth mode of electrical tree. The observation results of partial discharge during electrical tree growth also corresponded with this phenomenon. A viewpoint was proposed that the increase of shallow trap and the change of electrical tree´s conductivity are the primary cause of the emergence and development of electrical tree being inhibited. The results in this paper provide useful references for revealing the electrical tree initiation and growth mechanism, and for finding the material or method which can inhibit electrical tree.