Thermal Properties of Heat Conductive Silicone Rubber Filled with Hybrid Fillers

The thermal conductivities of vinyl endblocked polymethylsiloxane reinforced with silicone nitride (Si3N4) particles alone or in combination with silicone carbide whisker (SiCw) were investigated in this article. The results indicate that the silicone rubber incorporating of 50 vol% hybrid Si3N4 particles of different sizes at an optimal weight ratio exhibited the highest thermal conductivity of 1.48 W/m K compared to each single particle size filler used only; moreover, the combined use of hybrid Si3N4 and SiCw with the weight ratio of 9:1 provided the composites with higher thermal conductivity due to the structuring filler in hybrid fillers, improved thermal stability and reduced coefficient of thermal expansion (CTE) for comparison with the hybrid Si3N4 particles used alone. In addition, the surface treatment of the hybrid fillers with 3-methacryloyloxy-propyltrimethoxysilane enhanced the thermal conductivity and reduced CTE of the composites.