Fabrication, mechanical, thermal, and electrical characterization of epoxy/silica composites for high-voltage insulation

Abstract

For improved performance of epoxy, its composites were studied for high-voltage insulation. Epoxy composites may offer several advantages over neat epoxy and ceramic materials. We fabricated nano- and microepoxy/silica composites with 5 wt% nanosilica and 20 wt% microsilica, respectively. The composites and neat epoxy were studied for thermal, mechanical, and electrical properties. A thermogravimetric analyzer was used for analyzing wt% loss with temperature. Tensile and hardness tests were performed according to DIN 53504/ASTM D412 and DIN 53505/ASTM D2240 standards, respectively. Electrical properties such as dielectric strength and resistivity were tested according to IEC-60243-1 and ASTM D257/IEC 60093 standards, respectively. Neat epoxy, microcomposite, and nanocomposite showed 50% weight loss at 392°C, 410°C, and 421°C, respectively. At 550°C, nanocomposite remained at 20% of its initial weight whereas neat epoxy and microcomposite remained at 10% of their initial weights. Microcomposite and nanocomposite showed tensile strengths of 65.7 Mpa and 69.3 Mpa, respectively. Enhancements of 8% and 19% in dielectric strength were recorded for microcomposites and nanocomposites, respectively. Nanosilica greatly improved surface and volume resistivity whereas microsilica showed negligible effect on resistivity.