AC Corona Degradation of Silicone Rubber Nanocomposites at Low Air Pressure

Abstract

Corona discharges get accelerated at low air pressure conditions leading to severe aging of the polymeric housing material, eventually causing the failure of the insulator. In this article, the effect of ac corona on different silicone rubber (SiR) micro- and nanocomposite samples at low pressure is studied. Micro alumina trihydrate (ATH), nano-titanium dioxide (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), and nano-silica are used as filler materials in varying concentrations. This article compares the filler materials for nanocomposite preparation based on their performance in low-pressure conditions. It is observed that the decrease in pressure results in increased corona discharges and loss of hydrophobicity in the samples. The formation of carboxylic acid is evident from the Fourier transform infrared spectroscopy (FTIR) for the treated samples. The performance of silica nanocomposite with 5 wt% loading is better than the silica nanocomposite with 3 wt% loading. Crack width, surface roughness, and physicochemical changes were significantly reduced in silicone dioxide filled SiR (SSR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5%</sub> ) when compared to other silica and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -filled samples at low pressure. The SiR samples filled with 5 wt% nano-silica perform better in terms of resisting corona-induced degradation at low pressure.