Accelerated Acid-Water Aging of RTV Silicone Rubber Coatings

The paper reports on tests done on four commercial room-temperature vulcanized (RTV) silicone rubber high voltage insulator coatings aimed at achieving information on the relative performance of the coatings and the effect of acid-water on the surface degradation. The initial characterization of the coatings includes the identification of the primary filler type, concentration of filler, the amount of free fluid, and the molecular make-up of the free fluid. Soxhlet extraction and gas chromatography tests show considerable depletion of fluid after accelerated aging tests in acid-water and the associated depolymerization on the properties is assessed by changes in hardness. The effect of acid-water aging on the hydrophobicity is assessed by measurements of the static contact angle. The relative comparison of LMW of acid-water aged to field aged coatings gives an idea of the aging process in the field.