Suppression of Surface Charge Accumulation of Epoxy Resin Nanocomposites by SiO2 Nanoparticle Surface Grafting

Abstract

In order to find a nanodielectric capable of suppressing the surface charge accumulation, silica nanoparticles were modified with octamethyl cyclotetrasiloxane (D4) and hexamethyldisilazane (HMDS), and were doped into epoxy resin. The Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) were applied in the present article to investigate the variation of surface functional groups and structures of SiO2 nanoparticles before and after grafting. The surface charge accumulation, isothermal surface potential decay, and the volume resistivity were monitored to investigate the variation of main parameters, including the surface charge density, trap level, and the volume resistivity of different nanodielectrics. It is found that the surface charge accumulation of the epoxy nanocomposite dielectric can be remarkably inhibited after implementation of the surface grafting. Based on the performed analysis, SiO2 nanoparticles can produce deep traps in the epoxy after modifying with silane coupling agents. Obtained results show that the deep traps easily trap charges, limit the movement of charge carriers, increase the volume resistivity, increase the volume resistivity, and reduce the solid side bulk current of the insulator. It is concluded that application of SiO2 nanoparticles for the surface grifting effectively suppresses the surface charge accumulation on the epoxy resin surface.