Micro-AlN/nano-SiO₂ co-filled silicone rubber composites with high thermal stability and excellent dielectric properties

Silicone rubber (SR) is the most promising polymer for outdoor insulation but in neat form, it has low thermal stability and poor erosion resistance which restricts its outdoor applications. In this work, we explored the high thermal stability and excellent dielectric properties of SR co-filled with micron-AlN and nano-SiO₂. Samples of SR composites with different mixture (micro, nano and micro/nano co-filled) are fabricated by mixing techniques of mechanical stirring followed by sonication. Test results show that there is a significant escalation in the corresponding temperature of 5%, 25% and 50% weight loss. Besides, it is noticed a significant increment in residual percentage weight of the polymer component of co-filled composites. Moreover, co-filled composites show no major variations in the real permittivity but they offer lower dielectric loss relative to AlN30m. AlNmn3 and AlNmn4 are found to be the most promising co-filled composites for high thermal stability and dielectric properties, respectively, which makes them suitable for electrical insulation purposes.