The Research Of Modified Carbon Fiber/Epoxy Resin Composite By Adding Functional Carbon Nanotube Into Sizing Agents

Carbon fibers(CF) enhanced polymer composites have series of advantages, high specific strength and modules, thermo-stability, anti-corrosion, anti-fatigue, etc. while it also has less functional groups and low surface energy so that CF has low invasion with resin matrix, which has limited the application of the composites. Carbon nanotubes (CNT) also has a number of merits, a very high strength and toughness, low density, resistance to acid and alkali, high thermal stability, both metallic conductivity and semiconductor properties. Therefore, we choose CNT as enhancer to enhance the property of CF, modify the interface properties, and strengthen the properties of the whole composites. In this paper, CFs is immersed in aqueous dispersion of sizing agents, in which also has CNTs dispersed. In this way, CNTs may be deposited onto the surface with sizing agent and modify the surface property of CFs. The main work is shown as follows:1. Preparation of aqueous dispersion of sizing agents, and research suitable technological parameter, such as concentration and dipping time. After the test, we choose 3% volume fraction and 60s dipping time as final parameter.2. Disperse CNTs into aqueous dispersion of sizing agents and immerse CF into it to modify CFs. In fragmentation test, we find that Carboxylation functional CNTs has apparent reinforcement to fiber’s interfacial shear strength(IFSS), which is raised to 62.35MPa from original 50.31MPa, while Amide functional CNTs have an opposite effect. When adding Amide functional CNTs, the IFSS decreased.3. Prepare the modified CF/epoxy resin composites, and research the effects on different functional groups and concentration of CNTs in dispersion. In the test, both Carboxylation functional CNTs and Amide functional CNTs have a great increase on flexible strength, flexible modules and inter-laminar shear strength (ILSS) of the composites, in which Carboxylation functional CNTs have a more superior increase for the composites. In different concentration of CNTs dispersion modified CFRP, the CFs coated by a content of 0.5wt% CNTs sizing agent have better performance.