Synergistic Treatment Of Carbon Fiber Surface By Electrochemical Modification And Sizing Agent Application

Carbon fibers are often used as reinforced phases of composite materials.But the surface of chemical inert is difficult to be covered by resin,the compatibility of the resin is poor and it is difficult to form a good phase interface.However,the degree of interface bonding between the composites and the matrix determines whether the load can be effectively transferred between the matrix and the reinforcement phase of the composite,which directly afects the mechanical properties of the composite.In order to solve this problem,a synergistic processing method combining electrochemical treatment with sizing agent and physical chemistry is put forward to process the surface of carbon fiber,so as to improve the interfacial bonding strength between carbon fiber and resin matrix.Firstly,the modified epoxy resin E44 and the hydrophilic group were introduced,and the modified epoxy resin carbon fiber size was prepared.The physicochemical properties of modified epoxy resin emulsion were studied to obtain the best process parameters used as carbon fiber slurry.The products were analyzed by infrared spectrometer.The final product modified epoxy resin was proved by the contrast analysis of infrared spectrum and the water solubility of the products.The stability of emulsion was tested by centrifuge.The surface tension of emulsion was tested by surface tension tester.The particle size of emulsion was tested by laser particle size analyzer.The contact angle of emulsion on fiber surface was tested by contact angle meter.It is found that epoxy resin value is 0.06mol/100g and the concentration of emulsion is 1wt%is the best process parameter of modified epoxy resin as carbon fiber sizing agent.Secondly,the surface of carbon fiber is treated by two step cooperative treatment.The results show that the carbon fiber surface by the first step after electrochemical treatment,the carbon fiber surface becomes more rough,is conducive to the spread of the carbon fiber surface sizing agent,and the formation of the groove structure can also increase the sizing agent and the friction coefficient of carbon fiber surface,improve the combination of force.After second steps of sizing agent treatment,the number of surface active functional groups of carbon fiber increased,and the molecular film formed on the surface of the fiber could act as a coupling agent,which increased the adsorption and cohesive force.It can improve the interfacial bonding force between the carbon fiber and the resin matrix.And the sizing agent can repair the damage caused by electrochemical treatment to the surface of carbon fiber and improve the strength of carbon fiber.Finally,a universal strength machine was applied to test the mechanical properties of the composites made of carbon fibers with different treatment methods,so as to assess the effect of self made slurry.The results show that the electrochemical treatment,sizing agent applied treatment,CO treatment of carbon fiber composite interlayer shear strength(ILSS)were increased by 89.8%,139%,156.6%;synergistic treatment effect was significantly better than that of other processing methods,provides a new method for improving the interfacial performance of composite materials.