Evaluation on surface degradation of silicone rubber using thermogravimetric analysis

Thermogravimetric analysis (TGA) was used to evaluate the surface degradation of polymer insulators designed for outdoor high voltage applications. Such insulators are usually formed as a composite of silicone matrix and inorganic materials, such as aluminum trihydrate (ATH) filler and/or fumed silica. However, the surface of insulators is subject to long-term degradation during outdoor use. This contribution describes an analytical technique which can be used to investigate surface degradation phenomena of filled silicones and provide a quantitative evaluation of the surface degradation. Comparison of the TGA curves for virgin silicone and field-aged silicone removed from an outdoor insulator indicated depolymerization-induced loss of the siloxane matrix must occur during field aging