Thermal Conductivity And Electrical Insulation Properties Of BN Filled Polymer Matrix Elastomer Composites

The rapid development of the new energy automobile industry puts forward higher requirements for charging time.Shortening the charging time will cause the core of the charging pile cable to accumulate a large amount of heat in a short time.If the heat is not dissipated in time,it will reduce the service life of charging pile cable,which can cause fires and other accidents in severe cases.Therefore,obtaining insulating materials with good electrical,mechanical and thermal properties is of great significance to solving the heat dissipation problem of charging pile cables.This article uses styrene-ethylene-butadiene-styrene(SEBS)to modify polypropylene(PP),with boron nitride nanosheets(BNNS)and boron nitride nanospheres as thermally conductive fillers,using melt blending and multi-layer hot pressing methods to build ABAB...A type thermally conductive paths in the SEBS/PP matrix to obtain high thermally conductive insulating composites.Characterize composites by SEM and DSC,use laser pulse method to test the thermal conductivity of composites with different content and different number of layers,and then use tensile test to test the mechanical properties of the multilayer composites,and test composites electrical conductivity current at different temperature,also dielectric temperature spectrum,and dielectric spectrum are tested.The experimental results show that in the SEM test,it can be observed that the number of layers of the composites increases,the layer thickness decreases,and there are no obvious defects such as bubbles between the layers.The orientation degree of BNNS along the direction perpendicular to the pressure increases;DSC test shows that the boron nitride(BN)particles have the function of heterogeneous nucleation and increase the crystallization temperature of the SEBS/PP matrix.Due to the overlap between the BN particles,a thermally conductive network is formed,and the melting point of the composites tends to decrease;The thermal conductivity test results show that when the content of nanosheets is 10phr and the boron nitride nanospheres is 5phr,the thermal conductivity of the 9-layer composites reaches 0.514W/m·K,which is 3times compared with the thermal conductivity of the SEBS/PP matrix;The tensile test shows that with the increase of the content of boron nitride nanospheres and the number of layers in the multilayer structure,the tensile strength and elongation at break of the composites decrease;The variable temperature conductivity experiment shows that when the temperature is lower than 100℃,the content of boron nitride nanospheres and the number of layers of the multilayer structure have little effect on the conductivity of the composites;The test results of the dielectric temperature spectrum and the dielectric spectrum show that the relative dielectric constant of the multilayer composites is maintained between 2.33～2.61 in the temperature range of20-140℃and the frequency range of 0.1-10~6Hz,and the loss of angular tangent value is maintained between 0.0003 and 0.0036,which has excellent dielectric properties.