Study On Preparation And Mechanical Properties Of Graphene/Carbon Fiber Micro-nano Muti-scale Reinforced Epoxy Resin Composites

Compared with other traditional materials,carbon fiber reinforced resin matrix composites have been widely used in aerospace,automotive industry,sports and leisure fields due to their advantages of light weight,high specific strength,high specific modulus,excellent fatigue resistance and strong design ability.With the rapid development of science and technology,people have higher and higher requirements on the mechanical properties of carbon fiber composite products.However,the interface structure and performance of the composite material will directly affect the mechanical properties of the carbon fiber composite material.Therefore,the design and optimization of the interface structure is the key to promote the performance improvement of the composite material.As we all know,the interface is the "bond" connecting the matrix and the reinforcing fiber of the carbon fiber resin matrix composite material.A good interface can effectively improve the efficiency of load transfer from the matrix to the reinforcing fiber and eliminate the effect of stress concentration on the mechanical properties of the composite material.The formation of the interface depends on the wetting effect and bonding ability of the resin matrix on the surface of the carbon fiber,so it is particularly important to improve the wetting of the resin matrix on the surface of the fiber.In recent years,with the in-depth study of carbon nanomaterials such as fullerenes,carbon nanotubes and graphene sheets,its excellent mechanical properties and large specific surface area make it often used as a secondary reinforcement of composite materials.In this paper,based on the concept of multi-scale reinforcement,graphene nanosheets with the largest specific surface area and excellent mechanical properties are used as secondary reinforcement to modify the resin matrix and carbon fiber surface to improve the wetting effect of the resin on the fiber surface,and the mechanical properties of the carbon fiber composite material can be improved by adjusting the interface structure and chemical compatibility of the composite material.Based on this,the research contents of this paper are as follows:(1)Amino and epoxy functionalized graphene sheets are prepared by surface treatment of graphene sheets with KH560 and NH3H2O.The results show that after GNS is functionalized,its dispersibility in solvents and epoxy resins is improved,and after the GNS is treated with ammonia,N is introduced on its surface,and the O/C increases from 23.90 to 27.87.In addition,the use of KH560 grafted graphene sheet can introduce long-chain alkyl and epoxy groups on its surface to improve the dispersion of graphene in the epoxy resin matrix.(2)The functionalized graphene sheets are used to modify the epoxy resin,and then the carbon fiber reinforced functionalized graphene modified epoxy resin composites are obtained by carbon fiber reinforcement.As a result,it was found that the introduction of EMGNS reduced the surface tension of the epoxy resin matrix at 50? from 48.05 mN/m to 39.48 mN/m.At the same time,using 0.3 wt%EMGNS modified epoxy resin,so that the carbon fiber reinforced epoxy functional graphene modified epoxy resin composite flexural strength and flexural modulus reached a maximum of 1665 MPa and 140.17GPa,Compared with no modification of the resin matrix with epoxidized graphene,it was increased by 22.49%and 12.29%,respectively.Using 0.2 wt%GO to modify the epoxy resin matrix,the ILSS of the carbon fiber reinforced graphene oxide modified epoxy resin composite material can reach a maximum value of 92.20 MPa,which is an increase of 18.08%compared with that without graphene oxide modification.(3)The carbon fiber is treated with a sizing agent containing functionalized graphene to increase the surface free energy and roughness of carbon fiber,and improve the mechanical chimerism and interface bonding performance.When the concentration of aminated graphene in the sizing agent is 0.5 wt%,the bending strength,flexural modulus and ILSS of the carbon fiber reinforced pure epoxy resin composite can be increased to 1584.57 MPa,148.79 GPa and 88.47 MPa,respectively.When the aminated graphene sheet was not added to the sizing agent,it increased by 15.64%,17.07%,and 10.27%,respectively.