电力用硅橡胶复合绝缘子（SiR）在运行过程中会遇到雷击或火灾等情况，SiR在不同温度热解后发生膨胀和开裂等复杂变化而失效。然而，SiR的热解性能与这些变化的微观原因尚不明确。文章探讨了SiR在不同温度下的热降解过程，探究热解温度与SiR的结构、力学性能和表面疏水性之间的关系。通过同步热分析仪对SiR的热稳定性进行研究。结果表明：随着热解温度的升高，SiR的微观结构发生了显著变化。由于热解气体的释放以及SiR内部发生分子交联，SiR表面产生大量孔隙，硅橡胶交联度下降，拉伸性能降低。热解温度在300 ℃以上时，热解后SiR的力学性能明显下降，C—H键急剧减少。

Silicone rubber composite insulators (SiR) for electric power will encounter lightning strike or fire during operation, and SiR will fail due to complex changes such as expansion and cracking after pyrolysis at different temperatures. However, the pyrolysis performance of SiR and the microscopic reasons for these changes are still unclear. In this paper, the thermal degradation of SiR at different temperatures was discussed, and the relationship between pyrolysis temperature and the structure, mechanical properties and surface hydrophobicity of SiR was explored. The thermal stability of SiR was studied by synchronous thermal analyzer. The results show that the microstructure of SiR changes significantly with the increase of pyrolysis temperature. Due to the release of pyrolysis gas and molecular crosslinking in SiR, a large number of pores are produced on the surface of SiR, and the crosslinking degree and tensile properties of silicone rubber decrease. When the pyrolysis temperature is above 300 ℃, the mechanical properties and C—H bonds of the pyrolyzed SiR decrease obviously.