温度对硅橡胶电树枝自恢复特性的影响机制

The self-recovery characteristics and mechanisms of electrical trees in silicone rubber(SiR)are still unclear, and are studied herein at different temperature(30 ℃-180 ℃). The self-recovery and regrowth of electrical trees in SiR are observed. The self-recovery mechanisms are explained in combination with the variation of mechanical characteristics and crosslinking density of electrical trees in SiR during the self-recovery. The results show that parts of branches in the electrical tree gradually degrade and finally disappear without the interventions of healing fillers and external electrical-magnetic fields. The self-recovery characteristics vary in different stages. In the first stage(0 h-72 h), the rate of self-recovery is relatively high and has a negative correlation with temperature. In the second stage(72 h-432 h), the rate of self-recovery is relatively low and has a positive correlation with temperature. In the third stage(432 h-600 h), the rate of self-recovery is close to zero. The rate difference in different stages results from the difference in the primary inducement of self-recovery. In the first stage, the self-recovery mainly depends on the cooling shrinkage of gases in tree channels and the flow of gases from the side branches to the main channels. In the second stage, the self-recovery is mainly due to the loss of gases in channels and the elastic shrinkage of the channel walls. Increased temperature could hinder the cooling shrinkage of the gases in tree channels, while it can also intensify the flow of gases and elastic recovery of the channel walls, leading to the divergences in the temperature dependences of the self-recovery rate in different stages.