Construction Method Of Boron Nitride Orientation Heat Conduction Network In Diphenyl Liquid Crystal Modified Epoxy Resin

Epoxy resin has the advantages of strong chemical corrosion resistance and high electrical insulation,and is widely used in the field of electrical equipment insulation and electronic packaging.Epoxy resin does not have good thermal conductivity and poor toughness,which leads to poor thermal conductivity of epoxy-impregnated power equipment and is easy to crack under stress.Therefore,research on epoxy resins with high thermal conductivity and good mechanical properties has attracted extensive research attention.In this paper,in view of the problems of poor thermal conductivity and insufficient mechanical toughness in the application of epoxy resin,combined with the liquid crystal composite toughening technology,the construction method of the three-dimensional conductive thermal network of the filler in the epoxy resin matrix was studied,and both good thermal conductivity and mechanically toughness epoxy resin composites has studied the comprehensive performance of the composite material such as thermal conductivity,dielectric and mechanics.The main contents of the paper include:(1)The preparation method of biphenyl liquid crystal(BLCER)toughened modified epoxy resin was studied,and the influence of biphenyl liquid crystal on the mechanical,thermal stability and thermal conductivity of epoxy resin was tested.The results show that the mechanical toughness,thermal stability and thermal conductivity of epoxy resin increase significantly with the increase of biphenyl type liquid crystal content.Polarized light microscopy observations show that evenly dispersed,rigid rod-shaped liquid crystal domains appear in the liquid crystal modified epoxy resin,and the size and number of the liquid crystal domains increase with the increase of BLCER content.The liquid crystal domains enhance the crystalline and order of the epoxy resin,and enhance the physical and chemical properties of the epoxy resin such as thermal conductivity and mechanics.(2)The construction method of 3D-BNNSs oriented thermal network is studied Developed the ultrasonic physical peeling technology of boron nitride nanosheets(BNNSs)and the dispersion method of boron nitride nanosheets/cellulose suspension,built a three-dimensional oriented nano boron nitride thermal network freezing orientation platform,and prepared 3D-BNNSs aerogel with different BNNSs content.The results show that using dimethylformamide(DMF)solution as the stripping agent,physical ultrasound can be used to obtain layered BNNSs with a thickness of nanometers.Porous structure,the pore size is about 10 um,and the longitudinal direction is oriented parallel structure,which is distributed at 90° with the substrate.(3)The physical,chemical and dielectric properties of three-dimensional BNNSs/liquid crystal modified epoxy resin were studied.The results show that3D-BNNSs can significantly improve the thermal conductivity of liquid crystal modified epoxy resin compared with liquid crystal modified epoxy resin filled with BNNSs randomly.When the BNNSs filling amount is 8 wt%,the thermal conductivity of the liquid crystal modified composite epoxy resin in the thickness direction is 0.983W/(m·K),which is six times that of tranditional epoxy resin.At the same time,the mechanical toughness and power frequency breakdown strength of 3D-BNNSs/liquid crystal modified epoxy resin have been improved.The above research results show that the research on the three-dimensional BNNSs oriented thermal network in the liquid crystal modified epoxy resin not only maintains the electrical insulation performance of the epoxy resin,but also improves its thermal conductivity and mechanical toughness.