Study On Carbon Nanotube/Carbon Fiber Multi-Scale Reinforcement Composite

Compared with traditional CFRP(Carbon Fiber Reinforced Polymer), carbon nanotube/carbon fiber multi-scale reinforcement composites utilize mutual coordination role,not only increase the properties of polymer matrix, but also show higher strength and toughness, which have become a focus issue. Mechanical properties of composites depend largely on the performance of interfacial adhesion between carbon fiber reinforcement and polymer matrix, the better interfacial bonding properties the more effective of load transference, while the interfacial bonding properties rely on carbon fiber surface properties,the surface treatment of carbon fiber always be a widely concerned problem.There are many surface treatment methods of carbon fiber at present. In this article,carbon fiber was modified by nitric acid and ammonia/nitric acid. The treatment process was optimized by the surface morphology analyzing, roughness analyzing, functional groups analyzing and strength characterized with SEM, AFM, XPS, infiltration properties, tensile strength of single fiber test. Carbon fiber surface properties were characterized by monofilament fracture experiment and short beam shear test. Carbon nanotube/carbon fiber multi-scale reinforcement composite was prepared and tested by short beam shear test to study the enhancement of nanotube.The study showed that after surface treatment the roughness, the functional group content, and the infiltration properties increased, on the contrary, single fiber strength of the treated carbon fiber decreased. The interfacial bonding strength of carbon fiber modified by ammonia/nitric acid increased 49.2% than the unmodified ones and the ILSS(Inter-laminar Shear Strength) increased 14%, The result showed that the method of carbon fiber modified by ammonia/nitric acid was better. The ILSS of nanotube/carbon fiber multi-scale reinforcement increased about 25.5~28.2% with rein matrix containing nanotube at the percentage of 0.5%, which showed that the use of nanotube significantly increased the ILSS of composite.