Hydrophobicity Investigation and Life Estimation of Silicone Rubber Nanocomposites

Water repellency and service life of room temperature vulcanized silicone rubber (RTV-SiR) are of utmost importance for application as coating of outdoor insulators. Enhancements in these two characteristics may be achieved through RTV-SiR nanocomposites. In the present work nanocomposites of silicone rubber (SiR) at 2·5 and 5·0 wt.% were prepared and subjected to multiple accelerated stresses along with neat SiR for 9000 h in a specially fabricated chamber. The surface leakage current (LC) was recorded after each weathering cycle. The hydrophobicity after each weathering cycle was evaluated according to the method by the Swedish Transmission Research Institute. In the course of aging time, neat SiR was found with variation in hydrophobicity and a random rise in LC. In the cases of both nanocomposites, their properties indicated improvements over those of neat epoxy. By applying the regression technique over LC measurements, a relatively longer service life for the SiR nanocomposite with 5% nanosilica (nano-SiO2) was estimated.