Degradation Characteristics for HTV Silicone Rubber in a Condition of Low-dose Gamma Irradiation

The degradation of silicone rubber for external insulation under high-energy cosmic ray irradiation will threaten the safe operation of power transmission and transformation equipment. To study the effect of cosmic rays on silicone rubber at high altitudes, a low-dose gamma irradiation test with a cumulative irradiation dose of 0-9 kGy was carried out on high temperature vulcanization (HTV) silicone rubber specimens commonly used for external insulation. Spectroscopic studies, hydrophobicity tests, and mechanical tests were applied to the irradiated HTV silicone rubber. The results showed the surface reaction of silicone rubber at low cumulative irradiation dose generated Si-O structure and SiO2-like products, the methyl group in silicone rubber increased and the Si-C bond decreased during the irradiation process; after irradiation, fillers were precipitated on the surface, which was different from the generation of a large number of cloudy patterns at a high dose; the hydrophobicity and tensile properties of silicone rubber were improved compared with those of silicone rubber without irradiation and at high dose irradiation. The analysis shows that in the degradation by low-dose gamma irradiation, the non-terminal cross-linking structures between molecular chains as well as non-polar functional groups such as methyl groups are increased and the fillers are exposed.