The Study Of Coating Modification For PAN-Base High Modulus Carbon Fiber

Carbon fibers are often used as the reinforced material of composites in many areas, because they exhibit outstanding high tensile strength, high elastic modulus, and temperature,corrosion and fatigue resistance properties and so on. However, due to the carbon fiber surface is smooth, reactive functional groups are few and surface energy is low, the performance of the surface chemically is inert, and then wettability between the resin matrix and fiber is poor, resulting in interfacial adhesion between carbon fiber and resin phase is poor, which severely affected the composite overall performance. Therefore, we use the polymer coating on surface of carbon fiber to enhance the properties of the interface.In this paper, based on the property and design of inferface layer, we synthesized a latent curing agent (LCA) and the end epoxy polyurethane (EPU), than prepared a kind of epoxy emulsion that modified with different contents of LCA and EPU-acetone solution with different contents of curing agent as two kinds polymer coating that used for treatment on high-modulus carbon fiber. Through infrared absorption spectra analysis of the carbon fiber surface and polymer coating, chemical reaction occurred between the polymer coating and the fiber or resin; different kinds of polymer coatings has different affects on high modulus carbon fiber. After the epoxy resin emulsion contains the latent curing agent coating the carbon fiber, the surface wettability of the fiber has been improved; and shaping of the fiber is well; when content of the curing agent is 20%, the water absorption of the carbon fiber fell to 0.02%.Compared with the composites reinforced by unsized high modulus carbon fiber, the interlaminar shear strength (ILSS) of the sized high modulus carbon fiber/epoxy composites is improved. When the content of latent curing agent in epoxy resin emulsion reached 20%, the ILSS of the composites increased 8.6%; epoxy end polyurethane with the amount of triethylenetetramine is 70%, the ILSS of the composites increased 19.4%.SEM resultes demonstrate that the polymer coating enhances the interaction between high modulus carbon fiber and the matrix resin; improved the adhesive property of fiber/matrix compersites; the final combination between fiber and polymer coating became evenclosed, interfacial properties of the carbon fiber and resin matrix further improved; dynamic mechanical thermal analysis showed that coated the carbon fiber with polymer coating through cross-linked and cross-linking degree can improve interfacial properties of the composites, then inhance the composites performance.