Al₂O₃,hBN/VMQ Composites With Outstanding Damping Properties And Thermal Conductivity

In order to meet the requirements of vibration and noise reduction in the use of thermally conductive insulating silicone rubber composites,it is hoped that the composites not only has outstanding thermal conductivity,but also has excellent damping performance,providing a reliable heat dissipation path for electronic components and effective vibration damping protection.In order to prepare the silicone rubber composite with highly damping,thermal conductivity and comprehensive performance,this paper selected methyl vinyl silicone rubber?VMQ?as the matrix,2,5-dimethyl-2,5-bis?t-butylperoxy?hexane?DBPMH?as vulcanizing agent,spherical alumina?Al₂O₃?and hexagonal boron nitride?hBN?treated by silane coupling agent as fillers.The main contents of this paper are as follows:?1?The vulcanization characteristics of silicone rubber composites were studied.The suitable vulcanization conditions were as follows:the dosage of DBPMH was0.6%,the temperature was 160?,and the time was 16.4 min.?2?The effects of the type,dosage and hydrolysis time of silane coupling agent on the surface treatment of fillers were studied.The suitable amounts of Al₂O₃ and hBN silane coupling agents were 1.5%and 1.0%respectively,and the hydrolysis conditions were 35?x30min.The coupling agents hexadecyltrimethoxysilane?N3116?and vinyltrimethoxysilane?V171?were chemically bonded to the surface of the treated fillers.The actual grafting ratio of N3116 and V171 treated Al₂O₃ was 1.15%and0.66%.Similarly,the actual grafting rates of n3116 and V171 treated h BN were 0.86%and 0.50%,respectively.?3?The effects of surface treatment and volume fraction of Al₂O₃ on the properties of Al₂O₃/VMQ composites were investigated.The results show that the thermal conductivity of Al₂O₃/VMQ composites increases rapidly with the increase of filler loading,and the surface treatment of fillers can effectively improve the thermal conductivity of composites.At 60vol%loading,the properties of 171-Al₂O₃/VMQ composites were:thermal conductivity 1.02 W/?m·K?,tensile strength 2.84 MPa,elongation at break 37%,volume resistivity 2.1×10¹⁴?·cm,the maximum loss factor tan?Max=0.31@-28.7?.?4?The effect of hBN surface treatment and volume fraction on the properties of hBN/VMQ composites were investigated.The results show that V171 treatment improved the interfacial compatibility and interfacial interaction between hBN and VMQ matrix.The N3116 treatment reduces the damping properties of the composite,while the V171 treatment effectively improves the damping performance.With the increase of the volume fraction of V171-hBN,the damping performance of the composites first increases and then decreases.At 50vol%,the maximum loss factor tan?Max=0.65@143?,the temperature range of tan??0.5 was 37?¹80?,the thermal conductivity was 2.51 w/?m·k?,the tensile strength was 2.64 MPa,and the elongation at break was 108%,volume resistivity 2.1×10¹⁴?·cm,the hBN/VMQ composite has excellent damping performance and thermal conductivity,and good insulation properties.