| Graphite surfaces is two-dimensional crystal structure, formed of a close packing of carbon atoms. Each carbon atoms link with near carbon atoms by σ bond. Graphite have high mechanical properties, can effectively improve the mechanical properties of composite materials, elasticity, resistance to fatigue, thermal stability and hardness and other properties.The carbon fiber surface, the enforcement of carbon fiber/epoxy resin composite material, is smooth, has a chemically inert nature, and the base of invasive, epoxy resin is poor. Epoxy resin, the matrix phase of carbon fiber/epoxy resin composite material, has high cross linking density, presence of large internal stress, texture hard and brittle, poor impact resistance and other problems after curing. Because of the two reasons, the frangibility of composite materials is larger, the impact resistance is poor. Limit the application of epoxy resin/carbon fiber composite materials in high-tech fields. Therefore, improve the interface of carbon fiber and epoxy resin is to solve the primary problem of materials. Graphite surfaces are seen as ideal material modified epoxy resin/carbon fiber composite materials. Graphite surfaces between layer and layer has certain van der Waals force, is easy to produce each other together, and it is hard to even disperse in the epoxy resin. This limits the graphite in the use of epoxy resin/carbon fiber composite materials.Through the modification of the graphite, improving the graphite in the dispersion in epoxy resin. The paper closely around the interface problem in carbon fiber/epoxy resin composite materials.The research contents are as follows:(1)Under certain conditions, through the strong sulfuric acid, nitric acid mixed make graphite surfaces surface produce carboxyl and hydroxyl. By silane coupling agent KH-560modifying a-graphite, it can make the surface of the graphite graft epoxy groups and which realize the functionalization of graphite.(2)Using the mechanical mixing method, prepared the graphene/epoxy resin composite material, Curing process, structure and properties were characterized by thermo-gravimetric analyzer(TG), rotating rheometer、differential Scanning Calorimeters(DSC), scanning electron microscope(SEM) and universal testing machine. The relationship of properties and microstructure was been elaborate. The TG results showed that graphene joined, s-graphene content reached0.20%, the weightlessness rate of the modified epoxy resin reached32%. DSC test results:the glass transition temperature had a little change, graphene was added to the epoxy resin. Different heating rates by epoxy resin DSC displayed, Tp and Tf increased. Due to curing reaction speed is rapid, epoxy resin local soon crosslinked, the other chain period of epoxy resin could not react with the rest of the functional groups, desired enthalpy decreased gradually. Rheological test results show that:the graphene joined, epoxy resin viscosity becomes larger, the storage modulus increases. SEM results showed that modified graphene in epoxy resin/epoxy resin dispersed evenly. Epoxy resin tensile form is from the typical brittle fracture into ductile fracture.(3)According to the epoxy resin/carbon fiber composite materials, the two main toughening methods:namely of modifing epoxy resin, toughening composite material layers. Graphite was respectively dispersed in epoxy resin and homemade sizing agent, and carbon fiber was prepared after silk. The mechanical properties and toughening mechanism of carbon fiber were researched. The results show that the mechanical properties of carbon fiber that the graphene were dispersed in sizing agent were superior to directly disperse in the epoxy resin prepared, and the enhancement effect of Interface bonding performance is more obvious. |
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