The Study Of Carbon Fiber Reinforced Nylon Composites

Thermoplastic resin composites, as an important branch of composites, can be easily operated, reused and has a short production cycle. In addition to excellent mechanical properties, carbon fiber reinforced nylon composites (CFR-PA66) also have some characters such as excellent conductivity, wear-resistance and self lubrication, which can be used for wear-resistant and electromagnetic shielding materials and it would have a wide range of application.In this work, carbon fibers were respectively treated by electrochemical oxidation and electrochemical oxidation combined with ammonia treatment method. Short carbon fiber reinforced nylon composites were prepared by using twin-screw extruder and injection molding. The flexural strengths of electrochemical oxidation carbon fiber/PA composites and electrochemical oxidation-ammonia carbon fiber/PA composites were enhanced respectively by 1.26 times and 1.12 times comparing with the untreated ones. Functional groups on carbon fiber surface were analyzed by XPS. The strengthenning effects of different surface functional groups on carbon fiber composites materials were studied by single carbon fiber strength test, composite flexural strength test, fracture morphology analysis and the theoretical calculation of interfacial bonding strength. It was also found that the combining strength of nitrogen functional groups in nylon-66 matrix is larger than that of oxygen functional groups. Wear resistance of composites was improved as the carbon fiber volume increases. It also showed that the wear resistance of ammonia treated CF / PA 66 composites was superior to electrochemical oxidation-CF reinforced composites.Comprehensive performance of CFR-PA66 is decided by not only the reinforcement (carbon fiber), the matrix phase (nylon) but also the interface adhesive properties between carbon fiber and nylon. If the interface adhesive properties are good, the overall performance of the composites can be improved. Interfacial bonding between these two phases mainly depends on three kinds of forces (chemical bonding force, van der Waals force and mechanical interlocking). The improvement of interface performance is the key factor that should be considered during studying the composite materials. It is significant to find a more effective surface modification method in order to improve the interface infiltration and adhesion of carbon fiber Composite materials and the final performance.