Preparation And Properties Of The Thermal Conductive Silicone Rubber

With the rapid development of integrated technology and assembly technology in the field of electronic and electrical.The volume of the circuit and electronic components has been shrinking and the thermal conductivity of the interface materials put forward higher requirements. Conventional heat conducting materials are mostly metal materials, but the performance of metal materials in the process of corrosion resistance is poor, and the application in some fields is limited. Polymer materials have excellent performance of corrosion resistance, but due to the polymer materials is a poor conductor of heat, so single polymer materials is far below the requirements of the use of. Therefore, the preparation of high thermal conductive polymer materials with very high practical value. In many polymer materials, silicone rubber has stable chemical properties, high and low temperature resistance, high pressure resistance, ozone aging resistance, solvent resistance, radiation resistance, weather ability, physiological inert, high permeability and biological compatibility and other excellent properties, application field is more and more widely. Because of the research and manufacture of the thermal conductive silicone rubber was prepared with a great significance.This paper chooses four different morphologies of high thermal conductive fillers, study filler morphology and amount of the thermal conductivity of thermal conductive silicone rubber composite,-mechanical properties, thermal stability, crosslinking density; the same packing different particle size and different particle diameter compound on the properties of heat conductive silicone rubber composite influence; compound fillers with different morphology for the comprehensive performance of heat conductive silicone rubber composite materials. The main research contents and results are as follows:(1)Selection of platelet boron nitride and spherical alumina, irregular aluminum nitride particle, carbon fiber as filler of conductive silicon rubber composite. The research results show that:with increasing of filler content, four different morphologies fillers of high thermal conductive can improve the thermal conductivity of silicone rubber composite. Among them platelet boron nitride> irregular aluminum nitride> spherical alumina> carbon fiber. Platelet boron nitride filled 50vol%,The thermal conductivity of thermal conductive silicone rubber composite can reach 2.95 W/mK; from the SEM of silicon rubber composite can see platelet boron nitride in the silicone rubber matrix dispersion is better, and interfacial compatibility with matrix is good and particles contact in face to face, interfacial thermal resistance is smaller, the easier the formation of conductive network chain. The thermal stability of the composite materials filled with boron nitride and spherical alumina is better.(2) The Maxwell model and its modified model and Agari model were used to simulate the thermal conductivity of silicone rubber composites, and the results were compared with the experimental results. The results show that when the filler amount is small, the two models are applicable, but when the filler volume fraction increase gradually, Maxwell model is suitable for spherical alumina, carbon fiber, modified Maxwell model is suitable for platelet boron nitride, irregular aluminum nitride suitable.By Agari model predictive the formation of the network chains of thermal conductivity on the four different morphologies filler in the composite system. The results showed that thermal conductivity chains, boron nitride> aluminum nitride> alumina> carbon fiber formation, and coincide with the thermal conductivity test results.(3) The effect of boron nitride size on the properties of thermally conductive silicone rubber composites was studied. The results showed that the different particle sizes of boron nitride have the same trend on the thermal conductivity silicone rubber,with the increase of the volume fraction increases. When the the filler 30vol.% the padding threshold is reached. Thermal conductivity of larger size BN is bigger than that smaller when the filler volume fraction are the same, but 15μm and 30μm have little difference. Three different particle sizes of BN were mixed, and the results showed that the thermal conductivity of silicone rubber composites was maximum when 30μm:15μm=1:2.(4) Preparation of thermal conductive silicone rubber composite by mixed of platelet boron nitride and irregular aluminum nitride.The results show that when BN:AlN=1:l,the thermal conductivity maximum 1.34 W/mK was greater than single AIN filled composite materials and reduce the cost of packing at the same time.