Effect of vulcanization system on thermal aging property of silicone rubber

In order to explore the effects of different vulcanization systems on the thermal aging properties of silicone rubber used for enhanced insulation of cable accessories, silicone rubber was used for enhanced insulation of 35 kV cable accessories as the research object, and peroxide and hydrosilane addition vulcanization systems were used to produce vulcanized silicone rubber samples and carry out thermal aging tests to compare and analyze the mechanical and electrical properties of the rubber. In the early stage of thermal aging, the oxidative cross-linking reaction of molecular side chains and the re-cross-linking reaction between molecular chains occurred in both silicone rubber vulcanization systems, and the cross-linking degree increased. In the later stage of thermal aging, the cross-linking system structure and molecular chain were destroyed, and the cross-linking degree decreased. The research and test results show that the tensile strength and elongation at break of silicone rubber samples gradually decrease with the increase of thermal aging time, the conductivity decreases first and then increases with the increase of temperature, the relative dielectric constant increases gradually and decreases with the increase of temperature, the tangent of dielectric loss angle increases gradually and increases with the increase of temperature, and the breakdown field strength increases first and then decreases. The silicone rubber under the hydrosilane addition vulcanization system has always maintained high crosslinking degree and has better mechanical and electrical properties after thermal aging, while the silicone rubber under the peroxide vulcanization system produces strong acidic by-products during vulcanization and produces strong polar groups after thermal aging, resulting in the deterioration of the thermal aging performance of the silicone rubber. © 2024 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.