Surface Charge Accumulation and Trap Characteristics of SiO2/SR Composite

Silicone rubber (SR) is an insulating material widely used in DC cable accessories. Its interface is a weak area of insulation and there is a problem of charge accumulation. Hydrated silica (SiO
2
•nH
2
O) is a reinforcing agent commonly used in SR, and its main component is SiO
2
. This article is based on polymethylvinylsiloxane, doped with SiO
2
particles of different mass fractions. The attenuation of the isothermal surface potential of the sample was tested. Combined with the isothermal surface potential attenuation model, the trap characteristics of the sample are obtained. The results show that the doped SiO
2
introduces a large number of traps on the surface of the SR, among which deep traps are the main ones. Based on the principle of molecular dynamics, simulation calculations of related molecules were carried out, and the results were consistent with the experimental results. The Si-O-Si bond formed by SiO
2
and SR and the hydroxyl group on the surface of SiO
2
introduce impurity trap energy levels between the original forbidden band and conduction band, thereby affecting the surface charge transfer. The results of the research provide help for the design of DC cable accessories.