Moisture Diffusion Property and Moisture-induced Electrical Performances of Liquid Silicone Rubber

Abstract

Liquid silicon rubber (LSR) is a vital component of cable accessories and its dampness is one of the most important reasons for cable faults. Therefore, the study on moisture diffusion property and moisture-induced electrical performances of liquid silicone rubber is of great significance. In this paper, the diffusion model of water molecules in LSR and the influence of temperature on the diffusion process of water molecules were studied, then, the effect of water absorption on the electrical properties of liquid silicone rubber was investigated. The results indicate that the diffusion process conforms to Langmuir diffusion model, rather than the classical Fick diffusion model, which means that water exists in LSR in “free” state and “bound” state. Besides, the temperature affects the diffusion process of water molecule and the dissolution process of low-molecular-weight siloxane and filler particles in some extent, for which the saturated water absorption rate increases first and then decreases with increasing temperature. In addition, the water absorbed by LSR decreased the volume resistivity and AC breakdown strength of LSR, and increased the dielectric constant and loss tangent of LSR.