Preparation And Study Of Thermal Conductivity And Electrical Insulating Properties Of Al₂o₃/Silicone Rubber Composite

In the pursuit of smaller and thinner electronic products,rapid heat dissipation has become a key factor restricting the densification,miniaturization and high power of electronic components.Elastic thermal conductive material is a good solution to the heat dissipation problem in the fields of electronics and electrical.The heat dissipation of electronic components with complex surfaces requires that the thermal conductive medium has certain plasticity and elasticity,and at the same time the material is required to have high electrical insulation to prevent the internal current passing through other components.Hence the composite with polymer matrix and high thermal conductive filler were commonly used as elastic thermal conductive materials,and how to improve the thermal conductivity and other properties of such kind of filled polymer materials has been widely concerned and explored.In this paper,a variety of particle size of alumina,with good thermal conductivity,controllable cost and stability,are used with high thermal conductive carbon nanotubes as thermal conductive fillers,and silicone rubber with tolerance of wide temperature and good corrosion resistance is selected as polymer matrix.The influence of surface treatment,shape,particle size,addition amount,and its particle size grading of alumina,and mixing with CNTs,on the thermal conductivity and dielectric properties of the filled silicone rubber composite are studied systematically,and thus composite materials with excellent thermal and dielectric properties are then obtained.Firstly,the silicone rubber in this paper is fabricated via the addition reaction of polydimethylvinyl siloxane with catalyst,where a vinyl siloxane is used as the cross-linking agent.In the process of studying the curing behavior of the silicone rubber,it's found that the catalyst dosage in the total proportion of 8‰,with the ratio of hydrogen content in hydrogen-containing silicone oil to vinyl content in the system of1:1 and the temperature of 120?is the optimum proportion for preparing best molded silicone rubber.Then,further studies have shown that alumina after surface modification by silane coupling agent,with a spherical surface and a larger particle size has a more pronounced effect on the thermal conductivity of the composite at the same loading.Moreover,the thermal conductivity of the corresponding silicone rubber increases as the content of the alumina filler gradually increases,and a significant increase appears when the filler content reaches a certain value of 50 wt.%.Finally,it's found that for different content of alumina filler,the relative content ratio of alumina of 8?m to that of 80?m particle size in the best filling choice is about6:4.Furthermore,when Al₂O₃/CNTs hybrid filler is less than 10 wt.%,the best thermal conductivity and dielectric properties of silicone rubber composites are obtained when the content of CNTs is 0.27 wt.%.