Surface Recovery Investigation of Silicone Rubber Composites for Outdoor Electrical Insulation under Accelerated Temperature and Humidity

Abstract

Degradation of silicon rubber due to heat and humidity affect its performance in outdoor applications. To analyze the effects of high temperature and humidity on room temperature vulcanized (RTV) silicone rubber (SiR) and its composites, this study was performed. Five different sample compositions including neat silicone rubber (nSiR), microcomposites (15 wt% silica(SMC 15% SiO2) and 15 wt% ATH(SMC 15% ATH), nanocomposite (2.5 wt% silica(SNC 2.5% SiO2) and hybrid composite (10 wt% micro alumina trihydrate with 2 wt% nano silica(SMNC 10% ATH 2% SiO2) were prepared and subjected to 70 ˚C temperature and 80% relative humidity in an environmental chamber for 120 h. Contact angle, optical microscopy and Fourier transform infrared (FTIR) spectroscopy were employed to analyze the recovery properties before and after applying stresses. Different trends of degradation and recovery were observed for different concentrations of composites. Addition of fillers improved the overall performance of composites and SMC 15% ATH composite performed better than other composites. For high temperature and humidity, the ATH-based microcomposite was recommended over silica due to its superior thermal retardation properties of ATH. It has been proved that ATH filler is able to withstand high temperature and humidity.

Investigation of Ramped Compression Effect on the Dielectric Properties of Silicone Rubber Composites for the Coating of High-Voltage Insulation

“…Among the polymeric insulators, Room Temperature Vulcanized (RTV) silicone rubber is the best choice for the coating of high-voltage ceramic insulators [ 22 , 23 ]. The dielectric properties of silicone rubber are also influenced due to mechanical stresses.…”

Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements

“…Applying UV stress on silicone rubber in combination with high temperature can further accelerate the LMW diffusion [78]. In a more recent work [79], silicone rubber composites' hydrophobicity recovery improved with accelerated temperature and high humidity. However, it has been shown that accelerated weathering stresses can reduce a significant amount of LMW siloxanes even under dry conditions that could affect the hydrophobicity recovery [80].…”

Investigation on Electrical, Thermal, and Mechanical Properties of Silicone Rubber ATH Nanocomposites

“…The addition of filler shows a marginal reduction in the contact angle. The SR have high contact angle due to the low surface energy of the polar methyl groups in their side chain of SR having surface resistant to water and shows high hydrophobicity [21]. VOLUME XX, 2017…”

“…The hydrophobicity of silicone rubber recovery is by the diffusion of low molecular weight (LMW) components to the surface. The slow recovery of silicone rubber composites is due to the immobilization of LMW components by the fillers enhancing the recovery time high[21].…”