Conductivity And Mechanical Properties Of Polyaniline Modified Three-dimensional Carbon-based Conductive Filler/epoxy Resin Composites

In recent years,resin matrix composites have the excellent properties of good forming,high degree of design freedom,high strength,light quality,temperature resistance and corrosion resistance,which have caused a new craze in the field of conducting research.However,the traditional conductive fillers includes all kinds of metal powder,metal fiber,metal salts and other metal materials and graphite,carbon black,carbon fiber,graphene and other carbon materials such,they are usually in two-dimensional form filling in the resin matrix,and directly be mixed conducting resin matrix composite as conductive filler and there are dispersion difficulties,disordering arrangement,heavy density and poor compatibility with resin matrix interface problems,leading to poor conductive and mechanical properties,so as to restrict the development of conductive polymer matrix composites.According to the above problem,this study proposed 3D graphene structure(3DGFs)and carbon fiber papers conductive fillers,and used the polyaniline conductive filler to the conductive fillers of surface modification,resin transfer molding and vacuum assisted forming method are the preparation of epoxy resin matrix composites.By studying the microscopic appearance and chemical structure of the conductive filler before and after surface modification,the structural effect relationship between the conductive and mechanical properties of epoxy resin matrix composites is investigated.As systematically studied and compared,epoxy composites filled with modified 3DGFs presented an excellent balance between electrical conductivities and mechanical properties.Given all this,surface functionalization for 3DGFs using polyaniline layers was found to effectively improve the compatibility and interfacial bonding properties of 3DGFs in epoxy matrix.The existence of polyaniline interlayers in epoxy composites optimized interface micro-zone structure between 3DGFs and epoxy resin.The significant properties of epoxy composites arised from the cooperation of the 3D interconnected conductive networks,the conductive polyaniline interlayers and the interfacial bonding between 3DGFs and epoxy matrix.The main research contents of this study include the following aspects:(1)Freeze drying process was used to construct 3DGFs,the 3D graphene structure with high temperature heat treatment is stable and has a certain electrical conductivity,becoming the first kind of conductive filler in the study.Carbon fiber paper obtained directly from business is the second type of conductive filler in this research.(2)For three-dimensional graphene structure,chemical polymerization was used to polymerize polyaniline on the surface of the pore wall,and the transformation between the microstructure of three-dimensional graphene structures before and after modification was analyzed using the characterization method.For carbon paper,electrochemical polymerization was used to polymerize the different polymerization time on the surface of carbon paper,and the microstructure of carbon paper was analyzed by means of characterization method.The results show that the polyaniline prepared by chemical polymerization is attached to the surface of the pore wall of three-dimensional graphene structure by the layered structure of a few hundred nanometers.The polyaniline prepared by electropolymerization is wrapped around the surface of carbon fiber in the form of a fibrous net.(3)Epoxy matrix composites were prepared by resin transfer molding and vacuum assisted forming technology,and the changes in conductivity and mechanics of composite materials before and after modification were compared.The results indicate that the properties of the modified composite materials are the best in 3DGFs/epoxy matrix composites prepared by resin transfer molding process.Vacuum aided process preparation of carbon paper/epoxy composite,with the extension of polymerization time,the conductive and mechanical properties of the composite to strengthen gradually,when the optimal polymerization time reaches 10 min.(4)Using FE-SEM and accompanying EDS,contact angle and the theory of interfacial bonding to prove that the presence of polyaniline interlayers improves the interface bonding between conductive filler and epoxy resin.According to the analysis of DMA thermal stability analysis,contact angle test and the formation mode of interface micro-zone,the influence mechanism of modified conductive filler on adhesion properties of epoxy matrix composites was investigated.