Mechanistic insights into the thermal-mechanical aging of the interface of cross-linked polyethylene/silicone rubber

Cable accessory has the interface formed by cross-linked polyethylene (XLPE)/silicone rubber (SiR), which is prone to surface discharge and thus causes the failure of cable system. This article conducts the simulated experiment of thermal-mechanical aging on the interface of XLPE/SiR. The interfacial breakdown and dielectric properties under different aging states are analyzed. It is found the interfacial aging process of XLPE can be divided into the recrystallization stage and the oxidation reaction stage. The former contributes to the interfacial roughness and thus the better insulating performance, whereas the latter leads to degradation of interface, and thus the worse insulating performance. In addition, combined with the established electric field model for the interface, the differences between thermal-mechanical aging and individual thermal aging on the interface are discussed. The sample under thermal-mechanical aging reaches the maximum interfacial breakdown voltage later than that under individual thermal aging, but their performance tends to be consistent in the later stage of aging. The change of interface microstructure and its effects on electric properties of cross-linked polyethylene/silicone rubber under thermal-mechanical aging.image