Preparation Of Reactive Carbon Nanotubes And Research On Unidirectional Carbon Fiber Composites

Compared to traditional metal materials, fiber composites are widely used in aerospace, transportation, wind power, sports equipments due to its high strength, modulus and low density. As advanced anisotropic material, the mechanical properties along radial direction were lower than that along axial direction. Carbon nanotubes (CNTs) were considered to be ideal reinforced materials due to its excellent mechanical performance and used to be introduced into resin matrix to effectively improve the mechanical properties of fiber composites along radial direction. However, as-produced CNTs were easy to aggregate in resin because of its large specific surface area and surface tension and as a result, the application of CNTs in composites was limited.In this paper, on the basis of amino-functionalized multi-walled carbon nanotubes (MWCNTs-NH2), three different mono-functional epoxy compound n-butyl glycidyl ether (BGE), benzyl glycidyl ether (EP 692) and twelve-fourteen alkyl glycidyl ether (AGE) were grafted onto the surface of MWCNTs-NH2 to prepare active CNTs. The successful grafting of epoxy compound was confirmed by FTIR, XPS and TGA and the interface with different rigidity was formed between CNTs and resin. It was also demonstrated that activated CNTs exhibited lower polarity and better compatibility with epoxy than CNTs-NH2.The mechanical test found that the reactive CNTs had a more pronounced increase in flexural properties than MWCNTs-NH2. Compared to neat resin, the composites reinforced by MWCNTs-NH2 achieved 10.6% and 22.5% improvement in flexural strength and modulus with 0.5wt% addition loading while the improvements of composites reinforced by activated CNTs in flexural strength and modulus were as high as to 22.9% and 38.1% respectively. The much better effect of activated CNTs on mechanical properties was resulting from its better dispersion in resin. In addition, the introduction of epoxy compound onto the surface of MWCNTs-NH2 also had an influence on the interface bonding between T700 carbon fibers and resin matrix, inter-laminar shear strength (ILSS) of fiber composites was found to increase from 79MPa to 86.3MPa with 1wt% addition of activated CNTs compared to that with no CNTs addition.