Preparation And Properties Of Heat-resistant And Thermal Conductive Addition Silicone Rubber

With the development of science and technology,high performance materials are urgently demanded in electronic and electric products.Silicone rubber composites,which have good heat-resistant,thermal conductive and insulating properties,can improve the service life and operation stability of related devices.The related materials were investigated in this paper,and the main contents are as follows:The methyl vinyl silicone oil,phenyl vinyl silicone oil,fluorin vinyl silicone oil,and hydrogen silicone oil were used as raw materials.The effect of vinyl silicone oil type,type and amount of hydrogen silicone oil,catalyst dosage and reaction temperature on thermo-gravimetric curves,tensile strength,high temperature weight loss rate of silicone rubber were investigated.A reasonable formula and curing condition of heat resistant silicone rubber were as follows:phenyl vinyl silicone with 29wt%phenyl group as based silicone oil,hydrogen silicone oil with 1.5wt%hydrogen as crosslinking agent,0.2wt%catalyst,and 70 ?reaction temperature.The thermal conductive Al2O3 powders were surface treated with different silane coupling agents.The effect of surface treated Al2O3 on tensile strength,thermal conductivity,thermo-gravimetric curve and powder activation degree of silicone rubber composites were analysized.The suitable silane coupling agent is vinyl triethoxy siloxane(A-151),and the dosage is 1.0wt%.The thermal conductive index of the composites increases with the increasing of Al2O3 content.Nano CeO2,Fe2O3 and CuO were added to improve the heat resistance of the silicone rubber composites,but the composites heat resistance improving by the 3 kinds of inorganic additives is a little.Benzoyl peroxide,dicumyl peroxide,and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane(double 25)were added to further improve the heat resistance of the phenyl silicone rubber.When the amount of double 25 was 2%,the temperature of silicone rubber with mass loss of 1%increased considerably,and the weight loss rate at 240×12h was reduced by 58.7%by comparing with that of without adding.The insulation,heat conduction and heat resistance of the pilot heat-resistant and thermal conductive addition silicone rubber composites reached the design requirements.