Preparation Of Carbon Fiber/Silicone Rubber Composite And Its Thermal Conductivity

Nowadays,electronic devices are used in various industries.Highly integrated circuits inevitably lead to high heat flux.If the heat cannot be released in time,the temperature of electronic components will rise sharply.This leads to short service life,poor performance,and unreliable stability and reliability.Among the polymer gasket materials,silicone rubber stands out due to its relatively high thermal conductivity and good elasticity.Most conventional thermal interface materials on the market are made of silicone oil and silicone rubberThis paper takes the preparation of new silicone rubber materials with high thermal conductivity as the research object,and uses the masterbatch method to study the thermal conductivity of one-dimensional carbon fiber(CF)reinforced silicone rubber(SR)composite materials;It was analyzed and studied systematically from the ratio of raw materials,chemical modification and physical modification of three ways.Obtained three kinds of silicone rubber composite thermal interface materials with high thermal conductivity.(1)Silicone rubber is compounded with various single fillers(graphite,carbon fiber,boron nitride nanochips),and the short-term irradiation of the silicone rubber matrix with ultraviolet light is explored;(2)Exploration of the compounding of silicone rubber and dual-phase filler;(3)Compounded with rubber after graft modification on the surface of carbon fiber;The above three systems have been comprehensively analyzed and characterized in terms of filler morphology,thermal conductivity,rheological properties and mechanical properties,and the following conclusions are drawn.(1)The influence of the number of individual fillers(graphite,carbon fiber,boron nitride)on the properties of silicone rubber composites was discussed,and the changes in the properties of various fillers were compared,It is found that when more fillers are used,the thermal conductivity of the silicone rubber composite is higher.The addition of thermally conductive fillers increases the thermal conductivity and improves the connection of the thermal network,so that the silicone rubber molecules and fillers can transfer heat more effectively;Silicone rubber composites with more fillers have slower quality degradation at high temperatures,CF and expanded graphite have the best improvement in the burning resistance of silicone rubber composites;The addition of filler increases the storage modulus and loss modulus of the composite material,and the peak loss factor also increases;Examining the cross-section electron micrograph of CF fiber / SR composite material,it was found that the cross-section showed typical brittle fracture characteristics,the roughness of the brittle cross-section was large,the surface was uneven,fibers have the phenomenon of pulled out;The addition of fillers increases the active groups of silicone rubber,showing more peaks in the infrared spectrum,making the material easier to process;the dynamic thermomechanical analysis of the composite shows that filler filling can improve the damping performance of silicone rubber.(2)The thermal conductivity of silicone rubber composites after CF and two-dimensional fillers has been studied.The thermal conductivity of the silicone rubber composite material after the combination of BN and CF is improved compared to the single filler,The thermal conductivity value of the silicone rubber composite material after the combination of BN and CF is improved compared to the single filler,indicating that the combination of multi-dimensional fillers can connect the thermal conduction path to a certain extent,After CF and graphite are combined,the thermal conductivity of silicone rubber composite material is more significant;Regarding the heat resistance of the composite material,it can be concluded that the compounding of the double filler also reduces the decomposition and volatilization of BN itself at high temperature,reducing the quality of consumption from 90.4% to 84%;Observation electron micrographs show that the addition of dual-phase filler tends to improve the fiber-to-fiber and fiber-to-matrix pathways,providing a better thermal conduction path for connection.(3)The effect of graft modification on the thermal conductivity of CF/ silicone rubber composites was investigated,It is found that the thermal conductivity of the composite material made by grafting ND(Nanodiamond)with CF functionalized with MDI(Isocyanate)has improved;Contrast electron micrograph and crystallinity analysis confirmed that the nanodiamond was indeed loaded on the surface of the carbon fiber;The change in the ratio of carbon fiber functional groups before and after loading results in an increase in carbon fiber activity after ND loading;Infrared thermal imaging pictures can more intuitively observe the improvement of thermal conductivity;As the number of fibers in the composite increases,the tan ? gradually decreases,and the fiber restricts the movement of the rubber molecular chain.Through the study of thermally conductive silicone rubber,the comprehensive performance of thermally conductive silicone rubber materials is improved,and the temperature range of silicone rubber products is increased,it will be possible to prepare silicone rubber-based thermally conductive materials that meet the requirements of various complex environments.