Preparation And Research Of Thermally Conductive Polymer Materials Based On Modified Boron Nitride

With the development of the 5G era and the electronic devices with high integration,high density,and high power properties,T leads to the generation and accumulation of high heat,which seriously affects their service life.Therefore,it is necessary to ensure that electronic products have good heat dissipation capabilities.Simultaneously,it is of great significance to develop packaging materials with high thermal conductivity.Because of excellent insulation and chemical resistance,epoxy resin and silicone rubber have been widely used in the field of electronic packaging,but their low thermal conductivity is not beneficial to the heat dissipation of electronic devices.In order to improve the thermal conductivity of epoxy resin and silicone rubber,fillers with high thermal conductivity such as aluminum oxide,graphene,and hexagonal boron nitride are added to the matrix resin.Compared with aluminum oxide and graphene,hexagonal boron nitride as a two-dimensional nanosheet material,has both excellent thermal conductivity and dielectric properties,it could be an ideal thermal conductive filler.However,it has the defect of poor compatibility with the matrix resin,which seriously affects its dispersion in the matrix resin,and greatly hinders its further large-scale application.In this paper,aiming at the bottleneck problem of poor dispersibility of hexagonal boron nitride,a new type of boron nitride modification method is studied,and two type of high thermal-conductivity composite have been prepared,which used epoxy resin and silicone rubber commonly as basic resin.The specific research contents are as follows:(1)Study on Surface Modification of Hexagonal Boron Nitride.Based on the principle of non-covalent modification,this paper utilize the ?-? conjugation between quercetin and hexagonal boron nitride to modify the surface of hexagonal boron nitride.FT-IR,SEM,Zeta potential and other characterizations show that quercetin is adsorbed on boron nitride,forming a rough coating layer,thereby non-covalently modified hexagonal boron nitride was obtained.The compatibility and dispersion stability of FBN with solvents have been significantly improved.The results also shows that the dispersion stability time in ethanol and xylene/n-butanol systems has increased from 3h to 72 h and 48 h,respectively.(2)Research on FBN/Epoxy Composite.Using boron nitride before and after modification as raw materials,prepare different boron nitride/epoxy resin composites,explore the effect of modification treatment methods of boron nitride,the amount of boron nitride,and different scales of boron nitride on thermal conductivity of composite.The results shows that the thermal conductivity of the composites increases with the addition of the amount of boron nitride,and the micro-boron nitride has a better effect on the thermal conductivity of the composites than the nano-boron nitride;the mixed use of micron and nano-boron nitride can improve the thermal conductivity of composites better than a single size,when the ratio of micron boron nitride to nano boron nitride is 2:1 and the filling amount is 40wt%,the composite epoxy resin has the highest thermal conductivity of 2.385 W/(m·K).After studying the coating film properties of composite materials,it is found that with the increase of FBN content,the pencil hardness of the coating film increases from 2H to 4H,and the adhesion and impact resistance decrease from 0 and 50 cm to 1 and 45 cm,respectively.But it has little effect on the overall performance of the coating film.(3)Using IPDI,TMP and hydroxyl-terminated polydimethylsiloxane as raw materials,two modified silicone rubbers,linear type(S-RTV)and cross-linked type(C-RTV),are prepared.The experimental results show that,compared with unmodified silicone rubber,the glass transition temperature of the two modified silicone rubbers has a small increase,but mechanical properties such as tensile strength,shear strength,crosslink density,and hardness have been greatly improved.According to the optimal FBN addition ratio explored in(2),the FBN/C-RTV composite silicone rubber with high thermal conductivity was prepared by using C-RTV silicone rubber with the most excellent mechanical properties as the base rubber.The results shows that with the increase in the amount of FBN,the thermal conductivity of FBN/C-RTV composite silicone rubber also continues to increase.When the nitrogen FBN is filled with 25wt%,the thermal conductivity can be as high as 1.793W/(m·K).