Identification and Characterization of the Chalking Layer of High Temperature Vulcanized Silicone Rubber

As the material of sheds and sheaths of composite insulators, high temperature vulcanized (HTV) silicone rubber will face aging phenomenon as the operation time grows. Chalking is usually used as a presentation method of aging, but there are few studies on chalking phenomenon and its influencing factors, which are focused on in this paper. Firstly, the physical and chemical properties of chalking HTV silicone rubber are analyzed from outside to inside, which indicates that the content of C of the chalking sample decreases while O gets higher, and serious oxidation occurs. The main chain and side chain structures are destroyed, while the content of short chain siloxane with low molecule weight (LMW) increases significantly. The chalking layer contains a large amount of small siloxane, while the content of large long chain siloxane is low. This work can provide a useful reference for the performance evaluation, operation and maintenance of composite insulators.