电缆接头绝缘用硅橡胶热老化及超声特性

With its high elasticity and excellent electrical properties, silicone rubber is widely used in the main insulation of prefabricated cross-linked polyethylene high-voltage cable joints. However, the abnormal temperature rise for a long time will accelerate the aging of the material, resulting in the decline of its related properties, thereby causing accidents. In this paper, an accelerated thermal aging test of silicone rubber for insulation of prefabricated high-voltage cable joints was designed and carried out. The microstructure, mechanical properties, electrical properties and acoustic properties of silicone rubber after thermal aging were compared and analyzed. The results show that the residual crosslinking by-products of silicone rubber insulation of cable joints volatilize after thermal aging, the organic content of side chain decreases, and the crosslinking occurs between main chains. With the increase of aging temperature and time, the elongation at break and tensile strength of the samples will decrease, and the Young's modulus will increase gradually, resulting in poor compliance, hardening and loss of elasticity. The volume resistivity and relative permittivity will increase slightly, and the dielectric loss factor will decrease with the progress of thermal aging. The ultrasonic velocity will increase significantly after thermal aging, and the test results are in accordance with the relevant theoretical formula, which corresponds well with the change trend of Young's elastic modulus. It has a broad application prospect in evaluating the thermal aging state of silicone rubber insulation of cable joints.