Enhancement of Acid Stability of Silicone Elastomers by Using Inert Fillers

This paper shows a novel approach to reduce the aging of silicone elastomers for outdoor insulators by using different filler surface treatments and inert fillers such as barium sulphate (BaSO4). Silicone rubber composite insulators are used in overhead transmission lines (OHTL) since many years, however under specific environmental conditions, they can show a reduction of mechanical properties, embrittlement and the formation of superficial cracks. Besides other factors, these aging effects can be attributed to strong acids, which can be generated by high electrical field stresses and acidic pollution on the insulator surface. In this study, silicone elastomers used for outdoor insulation, were equipped with aluminum hydroxide with various surface treatments and inert fillers, which provokes a significant improvement of aging performance. Silicone elastomer compounds equipped with barium sulphate show improved aging resistance under acidic environment, like a reduced mass loss when immersed in concentrated nitric acid, decreased crack formation and enhanced stability of mechanical properties with comparable erosion resistance.