Study On The Construction And Heat Transfer Mechanism Of Anistropic Graphene Reinforced Resin Matrix Composites

In recent years,with the continuous development of electronic technology,the small size,high integration and high power of large-scale integrated circuits have become the direction of the development of various electronic components.In the aerospace field,continuous work at high temperature,high pressure,and high frequency places higher requirements on the thermal conductivity and mechanical properties of the material.Traditional thermally conductive resin have been difficult to meet this demand,while the emergence of graphene has brought new opportunities and challenges for thermally conductive resins.The thermal conductivity of single-layer graphene can reach 5300W/m K,which has the highest thermal conductivity among two-dimensional materials.However,due to the high van der Waals force between the graphene sheets,it is easy to agglomerate inside the resin,forming a large number of voids and affecting the thermal conductivity of the composite material.Therefore,how to improve the dispersibility of graphene in resin matrix has become an urgent issue.At the same time,in order to obtain higher thermal conductivity of the composite material,it is necessary to add a large amount of graphene inside the composite material,which will greatly reduce the mechanical properties of the composite material and limit the application prospect of the graphene-filled thermally conductive resin.In this paper,a highly oriented graphene macro-body was first prepared.The overlapping of the graphene sheets inside the macro-body laid the foundation for the realization of the thermal conduction path and the anisotropy of the composite material inside the composite.Then the composite was formed by combining the resin matrix with the graphene macro-body.The graphene/epoxy composite was prepared while ensuring that the macroscopic graphene structure was not destroyed.In order to explore the influence of different factors on the thermal conductivity of the composite material,this paper used Nan model based on the effective medium approximation method to simulate the thermal conductivity of the composite material.The specific research results are as follows:In this paper,graphene sponge and graphene film were used as graphene macro body to compound with epoxy resin to prepare graphene/epoxy composite.SEM analysis shows that the inside of the graphene sponge has a tubular structure,and the inside of the graphene film has a layered structure.Both macro-bodies are highly oriented,and the overlap of the graphene sheets inside them can form a thermal conduction path inside the composite material.When the mass fraction of graphene in the graphene sponge/epoxy resin composite is 0.8%,the axial thermal conductivity of the composite can reach 0.69W/m K,which is 3.3 times that of epoxy resin;the radial thermal conductivity can reach 0.11W/m K,which is 53% of epoxy resin,and reached the standard of thermal insulation material.The composite material shows obvious anisotropy.When the mass fraction of graphene in the graphene film/epoxy composite is 17%,the thermal conductivity of the composite material parallel to the graphene sheet is 8.34W/m K,which is 39.71 times that of the pure epoxy resin.The thermal conductivity of the composite material perpendicular to the graphene sheet is 1.31 W/m K,which is 6.24 times that of epoxy resin.The composite material exhibits anisotropy and high thermal conductivity.In this paper,the factors influencing the thermal conductivity of the composite material were discussed by using the Nan model,and the thermal conductivity of two kinds of graphene/epoxy composite materials in the experimental part are simulated.The increase of the graphene aspect ratio and the interface thermal resistance will decrease the thermal conductivity of the composite,while the increase of the thermal conductivity of graphene and its mass fraction will increase the thermal conductivity of the composite.However,when the thermal conductivity of graphene in the horizontal and vertical directions reaches 3000W/m K and 30W/m K,respectively,the increase in the thermal conductivity of graphene has little effect on the thermal conductivity of the composite.The Nan model is better for simulating the thermal conductivity of composite materials with lower graphene content.When the graphene content is higher,the error of the Nan model is larger.