Molecular Dynamics Simulation Of Thermal Conductivity Of Styrene Butadiene Rubber And Its Graphene Composites

With the development of electronics,aerospace,aviation and other fields,integrated circuits are developing rapidly,which is often accompanied by the problem of difficult heat dissipation.In addition,tire materials have higher and higher requirements on the thermal conductivity of polymer.However,the thermal conductivity of the polymer itself is very low,so improving the thermal conductivity of the polymer is very important for the application of the polymer in these fields.In this paper,styrene butadiene rubber,which is widely used in thermal interface materials and tire materials,is used as the matrix material,and the effects of chain structure,crosslinking,stretching and graphene addition on its thermal conductivity are studied by means of molecular dynamics simulation.The microscopic mechanism of thermal conductivity of polymer materials was discussed in order to provide theoretical prediction and guidance for the improvement of thermal conductivity of polymer materials.In view of the influence of SBR chain structure on its thermal conductivity,the thermal conductivity of SBR system with different styrene content was simulated,and the results showed that SBR thermal conductivity would decrease with the increase of styrene ratio,which was mainly caused by the decrease of the degree of freedom of the main chain.In addition,the increase of styrene content in the tensile process will decrease the thermal conductivity of the system.In view of the influence of styrene butadiene rubber cross-linking on its thermal conductivity,the change of the thermal conductivity of styrene butadiene rubber system with different cross-linking densities was simulated.The results showed that the thermal conductivity of styrene butadiene rubber system increased with cross-linking,and the increase of the thermal conductivity decreased with the increase of the content of benzene rings in styrene butadiene rubber.For stretching orientation of styrene-butadiene rubber,the influence of thermal conductivity was studied different tensile speed(0.5 nm/ns,5 nm/ns,50 nm/ns),different temperature(50 k to 400 k)on styrene butadiene rubber,the influence of thermal conductivity results showed that the tensile will make styrene-butadiene rubber thermal conductivity increases,and the greater the amplitude of the drawing speed,the greater the coefficient of thermal conductivity,this is mainly due to the main chain orientation degree increases along the drawing direction.According to the thermal anisotropy of SBR,it is found that the coefficient of thermal conductivity parallel to the tensile direction and perpendicular to the tensile direction has a linear relationship with the orientation.According to the styrene butadiene rubber at different temperatures,it was found that the optimum operating temperature of styrene butadiene rubber with different tensile ratios was different,and the thermal conductivity peak temperature of the system with larger tensile ratios was smaller.Finally based on thermal conductive filler of styrene-butadiene rubber,the influence of thermal conductivity simulation to study the different graphene quality grades,different sizes of graphene styrene-butadiene rubber composite material coefficient of thermal conductivity,the results show that composite material coefficient of thermal conductivity will increase with the increase of content of graphene,and at the same graphene mass fraction,the large volume of graphene layer made of composite material coefficient of thermal conductivity increase amplitude is bigger.