Study on thermal conductivities and mechanical properties of silicone/expanded graphite composites

Abstract

In this study, series of expanded graphite (EG)-filled silicone composites were prepared by the bulk mixing and the solution methods to investigate the effect of thermal conductive EG particles and preparation methods on thermal conductivity of resulting silicone composites. With increasing EG contents and sizes, the thermal conductivity increased, and the solution mixing method showed higher thermal conductivity than the bulk mixing method. At 10 wt% of EG 140 μm-filled silicone composites, the solution mixing method showed the thermal conductivity of 0.789 W/m·K, which was about 147% over one prepared by the bulk mixing method and 538% increase over the pure silicone polymer. FE-SEM experiment was carried out to explore the dispersion and network formation of EG fillers in the silicone matrix. Tensile and dynamic mechanical analysis were also performed to investigate the mechanical reinforcement of the silicone composites. All the results suggested that the network structure of EG with larger size could improve mechanical reinforcement by increasing the modulus and optimize mechanical properties while improving the thermal conductivity of composites.