Performance evaluation of alumina trihydrate and silica-filled silicone rubber composites for outdoor high-voltage insulations

Abstract

In recent years, silicone rubber-based composites have been widely investigated for outdoor applications dueto their promising insulating properties. However, mechanical, thermal, and tracking properties of pure silicone rubberare very poor, which restrains its application for long-term performance. In this research work, the influence of microsizedalumina trihydrate (ATH) and micro/nanosized silica (SiO2) fillers on mechanical, thermal, and electrical properties ofroom temperature vulcanized silicone rubber (RTV-SiR) has been studied. SiR-blends with varying amounts of ATHand SiO2 particles were prepared by blending in a two-roll mixing mill, compression molding, and postcuring processesin sequence. In order to evaluate relative tracking and erosion resistance of SiR-blends, an inclined plane test (IPT)was conducted in accordance with the ASTM D2303 standard procedure. Surface temperature distribution was recordedusing a Fluke-Ti25 infrared camera during IPT experiments. Thermogravimetric analysis was carried out to analyzethe thermal stability of ATH and silica-filled silicone rubber samples. Tensile strength, percent elongation at break,hardness, erosion, tracking resistance, and thermal properties were also investigated and discussed. Results showed thatthe mechanical, thermal, tracking, and erosion performances of SiR-blends are improved by the incorporation of ATHand silica particles, which is governed by filler type, size, and wt.% in the polymer matrix