石墨及其表面改性对硅橡胶导热性能的影响

用双辊混炼机将导热填料分散到聚甲基乙烯基硅氧烷中,再配以增强剂、硫化剂等,经模压硫化制得导热硅橡胶。研究了导热填料种类、石墨的表面改性和用量以及石墨与炭黑的复配对硅橡胶导热性和力学性能的影响。结果表明,在用量相同的情况下,导热填料的导热系数越高,其填充硅橡胶的导热性越好,且硅橡胶的导热系数随导热填料用量的增加而增大。石墨的表面改性改善了石墨与硅橡胶的界面相容性,使硅橡胶的力学性能和导热性都得到提高。不同粒径及颗粒形态的炭黑与石墨复合可改善硅橡胶的导热性和力学性能,导热硅橡胶的拉伸强度和扯断伸长率随复合填料中炭黑用量的增加而提高,当石墨与炭黑质量比为25/5时,硅橡胶的导热系数最高,综合性能较好。

Effect of graphite and its surface modification on thermal conductivity of silicone rubber

Thermal conductive filler with reinforcing agent and crosslinking agent was dispersed in poly(methylvinyl siloxane) using a two-roll mill and the thermal conductive silicone rubber was obtained after curing in a mould. Effects of filler species, content and surface modificaton of graphite and its combination with carbon black on the properties of silicone rubber were systematically investigated. The results showed that at the same filler content the higher the coefficient of themal conductivity of filler was, the better the thermal conductivity of silicone rubber was. The coefficient of thermal conductivity of silicone rubber increased with the increase of the filler content. The surface modification of graphite improved the interfacial compatibility between graphite and silicone rubber, therefore the thermal conductivity and mechanical properties of silicone rubber increased. The silicone rubber with the complexed filler of graphite and carbon black having different sizes and morphology exhibited better thermal conductivity and mechanical properties. When the mass ratio of graphite to carbon black was 25/5, silicone rubber had the highest coefficient of thermal conductivity, and the tensile strength and elongation at break increased with increasing the content of carbon black in the complexed filler.