Performance improvement in nano-alumina filled silicone rubber composites by using vinyl tri-methoxysilane

The performance of inorganic filler filled rubber composites is mainly affected by filler-rubber interface interactions. In this work, vinyl tri-methoxysilane (VTMS) was employed during the preparation of nano-alumina filled silicone rubber (SIR) composites, serving as the molecular bridge between SIR matrix and nano-alumina filler to strengthen the interfacial interaction. Through the reaction with the hydroxyl and carboxylic acid groups on the nano-alumina surface, VTMS connected the nano-alumina particles with the rubber chains during the curing process, improving the filler-rubber interaction while decreasing the filler-filler interaction. Compared to pristine nano-alumina filled SIR composites, the incorporation of VTMS resulted in better filler dispersion in the as-prepared composites, which exhibited enhancement of thermal conductivity, breakdown strength and mechanical properties, and reduction of dielectric constant and dielectric loss.