Improved electrical treeing properties of silicone rubber at high temperatures by grafting aromatic hydrocarbon voltage stabilizer

Abstract

Since the electrical tree initiation voltage of the silicone rubber decreases significantly at high temperatures, it is significant to improve the electrical treeing resistance of silicone rubber at high temperatures for its safe and stable operation as an insulating material. In this work, a voltage stabilizer named the 2-Allyl-4,6-dibenzoyl resorcinol was grafted onto the silicone rubber. Then, the electrical treeing properties of the silicone rubber grafted with a voltage stabilizer were measured at different temperatures. The results showed that the electrical tree initiation voltage increased by 14.5%, 42.5%, and 46.0% than that of unmodified silicone rubber at 30 °C, 50 °C, and 70 °C, respectively. Besides, the propagation structure of the electrical tree was prone to more branches. The space charge distribution exhibited that the silicone rubber grafted with the voltage stabilizer has fewer space charge injections. The trap density result demonstrated that the grafting of the voltage stabilizer significantly reduced the density of shallow traps inside the silicone rubber and increased the energy level and density of deep traps. The improved performance at high temperatures is due to the grafted rigid structure-benzene rings in the silicone rubber, reducing the degree of segment relaxation of the material at high temperatures.