Thermal Decomposition Characteristics of Silicone Rubber in In-Service Power Equipment: A Study Combining Experiments...

To investigate the thermal decomposition characteristics of high-temperature vulcanized silicone rubber (HTV) and liquid silicone rubber (LSR) under different aging conditions, scanning electron microscopy (SEM) and thermogravimetric analysis (TG) were employed to characterize the surface microstructure and chemical properties of silicone rubber samples that had been in service for 15 years. The influence of aging degree on the thermal stability of silicone rubber was initially investigated. ReaxFF-based reactive molecular dynamics simulations were conducted to analyze the decomposition pathways of silicone rubber under high-temperature conditions, as well as the dynamic evolution of decomposition products. In addition, key parameters-including glass transition temperature, mean square displacement, cohesive energy density, and free volume fraction-were calculated before and after decomposition using the Materials Studio platform. The results indicate that LSR exhibits higher thermal stability than HTV, while the thermal stability of both materials decreases after thermal decomposition. Furthermore, the variation in thermal stability was discussed based on these parameters from the perspectives of molecular mobility and intermolecular interactions. This research can provide a reference for the safety operation assessment, aging status determination, and high-temperature service reliability design of silicone rubber insulating materials.