The Preparation Of Carbon Fiber Multi-Scale Reinforcement

Carbon fiber (CF) is the carbon content in more than 90% of inorganic fiber, and by the compound process of resin matrix composite materials performance, had been widely used in aerospace, missiles and civilian areas. Mechanical properties of carbon fiber composites is closely related to the interface shear strength of carbon fiber and matrix, the surface of the untreated carbon fiber inertia big, weak interface bonding to the resin. The low shear strength and bending strength of the composite material affected the performance of carbon fiber composite material, so the carbon fiber was often for surface treatment. The purpose of this study:The surface of carbon fiber was treated by a variety of methods, to improve the mechanical properties and the interlaminar shear strength of the carbon fiber composite material. Carbon nanotubes, graphene has been the focus of the carbon materials research, which have excellent physical, chemical properties, and rich active functional groups can be got by processing and good dispersion. Through the carbon fiber surface processing, could significantly improve the interface bonding strength of carbon fiber and matrix resin.First of all, this article adopted continuous production of growth carbon nanotubes the carbon fiber surface for the carbon fiber surface modification, the method:The carbon nanotubes could be growth by chemical vapor deposition method in the carbon fiber surface. In this paper, after a detailed discussion and a large number of experimental studies, we determined the best continuous process:the use of low temperature combustion method to deal with the resin on the carbon fiber, choose ferrocene as catalyst, xylene as solvent; Choose 750℃, nitrogen purging, control the proportion of carbon and nitrogen gas; Carbon fiber wire walking speed is 8 m/h, carbon fiber through the quartz tube in a row, to achieve continuous growth of carbon nanotubes. SEM and HRTEM were used to characterize the obtained product. A layer of 20-100 nm in diameter, length is 2-5 um carbon nanotubes can be observed on the carbon fiber surface.A kind of carbon fiber/graphene oxide and carbon fiber/carbon nanotubes multi-scale reinforcement was prepared by "grafting to" method.1) the mechanism of the carbon fiber surface grafting carbon nanotubes as:we used ethylenediamine as intermediates, hydrothermal method, the acidification of carbon nanotubes grafted to the processing of carbon fiber; In this paper, after detailed experiment and discussion to determine the best technology of carbon fiber surface grafting carbon nanotube is:we took acid oxidized carbon nanotubes 0.03 g, In accordance with the carbon nanotubes:N, N-dimethyl formamide as 1 (g):the ratio of 1000 (ml), add 30 MLDMF in hot water kettle, in which a certain amount of ethylenediamine again, and then mixed solution under the condition of ultrasonic ultrasonic dispersion 1 h, adding carbon fiber to hot water kettle,180℃ reacted for 48 h, got the carbon fiber/carbon nanotubes multi-scale reinforcement.2) carbon fiber surface grafting graphene oxide:Silane coupling agent KH550 was used to deal with T300 carbon fiber surface which was used acid oxidation treatment, then put the carbon fiber in the graphene oxide which was prepared by improved Hummers method, through the heat treatment the graphene oxide would be grafted to the surface of carbon fiber surface. The structure and the functional groups of the carbon fiber surface was analyzed, we could find that graphene was coating on the surface of the carbon fiber by chemical bond, which improves the surface of carbon fibers, and the crystallite size decreases on the surface of the carbon fiber.The mechanical properties,the conductive and the interlaminar shear strength of carbon fiber reinforced resin matrix composites was also tested and analyzed, find that:1) the tensile strength of the carbon fiber surface after the growth of carbon nanotubes is reduced by 5.7%, the interlaminar shear strength of the composite material is increased by 46.0%;2) the interlaminar shear strength of the carbon fiber surface after grafting carbon nanotubes is increased by 49.2%; 3) the tensile strength of carbon fiber grafting graphene oxide is increased by 9.8%, the elongation at break is increased by 13.1%, the interlaminar shear strength is increased by 97.2%. The mechanical performance of the carbon fiber is improved after surface treatment.