Fabrication, characterization and aging influence on characteristics of high temperature vulcanized silicone rubber/silica hybrid composites for high voltage insulation

Abstract

The growing demand for substitute materials in the area of high voltage outdoor insulation is governed principally by the need to decrease overall cost while accomplishing all pre-requisite insulation properties. Aging of these insulators is most important behavior due to their unpredictable response in the presence of environmental stresses. In this perspective, polymer hybrid composite materials may offer significant advantages over polymer nanocomposites and microcomposites. This research work is emerged to enumerate the effect of hybrid silica fillers (nano-silica varying from 0 ~ 10% with an increment of 2% and with fixed 20% micro-silica) loading on the mechanical, thermal and electrical characteristics of HTV Silicone Rubber (SiR) based high voltage electrical outdoor insulation composites. SEM was performed for the morphological analysis of the composite material. The hybrid sample with 6% nano-silica and 20% micro-silica (S6) exhibited 29.88% improvement in the ultimate stress, highest breakdown strength of 26.6 kV mm−1, and 50% weight loss was recorded at highest of 575 °C temperature. Electrical properties such as volume and surface resistivity also showed considerable improvements for the same sample. A multistress environmental chamber was built for applying the specific aging conditions. All the samples were subjected to long term accelerated aging in the chamber for 5000 h. After exposure to accelerated multistress environment, the hybrid sample with 2% nano-silica showed least loss in electrical, mechanical, SEM and thermal characteristics.