Abstract
Recently, due to the rapid developments in miniaturization of electronic devices and integrated micro/nano-electro-mechanical systems (MEMs/NEMs), thermal managements in nanoscale have become a critical issue. Traditionally, the carbon-based materials are regarded as the potential candidates due to the high thermal conductivity. Therefore, they are extensively applied to the field of composites for enhancing the thermal conductivity and other properties of polymers. In this study, we used expanded graphite (EG) prepared by using chemical intercalation method and commercial diamond powder (DP) as reinforcements, silicone as polymer matrix. First, we fabricated EG/Silicone composite specimens by three-roll mill. Second, we used hexane as solvent to disperse DP uniformly in silicone, and fabricated DP/Silicone composite specimens by electrical-magnetic stirring. Finally, we combined above-mentioned methods to fabricate EG/DP/Silicone composites specimens. In experimental design, we filled different dimension degree and grain size of reinforcements in Silicone. We measured the thermal diffusivities of composites by laser flash method, in order to calculate the thermal conductivities of composites. The effects on the mechanisms of heat conduction were also discussed. In the other hand, we used four-point probe analysis system and thermogravimetric analysis to characterize the electric insulativity and thermal stability, respectively. Finally, we observed the morphology of crossection of composites by field emission scanning electron microscope. In this study, we used expanded graphite and diamond powder with particle size between 150-180 μm as filler filled into silicone together with 3 wt% and 50 wt%, respectively. In this case, we can obtain the highest thermal conductivity, 2.41 W/m∙K.