Preparation And Performance Regulation Of The Epoxy Resin-based Thermal Conductivity And Insulating Composites

With the rapid development of modern science and technology,electrical equipment is moving towards intelligent,high frequency and integration.At the same time,the unit heat generation of related components is also increasing,and the heat dissipation is getting more and more prominent.If the device works in high temperature environment for a long time,there are too much heat in the internal aggregation,which will reduce the performance of the equipment and its life,even increase heat failure to the equipment,therefore it is more urgent to get outstanding composites with high thermal conductivity and high electrical insulation.Polymer polymeric thermal conductivity materials such as epoxy resin have received widespread concern based on their excellent characteristics.However,its intrinsic thermal conductivity is relatively low,only about 0.1 W/m k-0.3W/m k,it cannot meet the requirements of heat dissipation.First,this paper prepares the 3D thermal network by the ammonium bicarbonate template method,its filler is micron boron nitride with high thermal conductivity and high electrical insulation,the cellulose bonds the skeleton,then the epoxy resin is selected as polymer.The composites are prepared by vacuum impregnation and thermal pressures.This research focus on the thermal conductivity,dielectric properties and high-frequency high voltage electric fields.The three-dimensional thermal network internally present in the composite material can greatly improve its cooling efficiency,when the BN filling is 40.9wt%,the thermal conductivity of the composite can reach 1.62W/m K,which is 800% higher than that of the epoxy resin.This paper uses a scanning electron microscope to observe the micro-morphology of the composite materials,finding the good compatibility between the filler and the substrate,also demonstrating the presence of the thermally conductive network.Meanwhile,the composite materials also have high glass transition temperature(117°C-122°C).The dielectric constant and dielectric losses of the composites increase.This paper explores the effects of filler filling,frequency and temperature on dielectric properties of composites.The introduction of micron fillers will generate interface defects,resulting in the increase of dielectric constant and dielectric loss;the unique threedimensional network structure can prevent the steering and motion of the dipole,making the dielectric properties of the composites maintain good.The composite materials maintain excellent electrical insulation performance.In the power frequency high voltage electric field,the breakdown field of the composite with 40.9wt% BN loading has reached 38.3k V/mm to meet the practical application requirements.Under high frequency high voltage electric fields,composite materials prepared in this paper have higher resistance,the breakdown time increment can be up to 403% compared to that of the neat epoxy resin,this reason is mainly due to that the heat transfer effect of thermal conductivity in the composite material,which is much greater than the heat generation effect brought by the increase in dielectric loss.And the long-term resistance time can effectively curb the occurrence of thermal shot.