Study On The Nanostructure Based On The Surface Of Carbon Fiber And The Properties Of Carbon Fiber Composites

Carbon fiber reinforced polymer composites have been widely used in many field such as aerospace industry. Automotive industry, steamship industry, Petroleum industry and chemical industry. The cohesive force between carbon fibers (CFs) and the matrix is weak because the CFs has small active specific surface area, low surface energy, and lipophobic suface. It much limites the applications of carbon fibers reinforced composites. To improve the adhesion behavior of the carbon fiber/matrix interface, grafting carbon nanotubes (CNTs) onto the carbon fibers to design a CNT/CF multi-scale structure has become a hot spot in recent years and attracted more and more attention.(1) A novel method is developed for grafting multiwall carbon nanotubes (MWNTs) onto the surface of polyacrylonitrile-based high strength (T300GB) carbon fiber. Functionalized MWNTs were well dispersed in the PVA solution and the carbon fiber was dip-coated in this solution. After heat treatment of the coated carbon fiber under a nitrogen atmosphere, MWNTs with carboxyl groups were grafted onto the functionalized carbon fiber via chemical interaction. The resulting materials were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Raman spectrum and mechanical testing. FESEM observations revealed uniform coverage of carbon nanotubes on carbon fiber. The carbon fiber grafted with MWNTs improved the tensile strength by15%with respect to the pristine carbon fiber. These results are supportive of good interfacial bonding between the carbon nanotubes (CNTs) and carbon fibre. The introduction of MWNTs onto the surface of carbon fiber may help to remedy the surface defects and reduce stress concentrations, resulting in improved tensile strength of the carbon fiber.(2) The main purpose of this paper is focused on the growth of carbon nanotube on the surface of carbon fiber, carbon cloth and carbon paper with different morphologies by chemical vapor deposition (CVD) method. In this process, the metal catalyst ferrocene was dissolved in a liquid hydrocarbon, Xylene, to form a feed solution. This solution was delivered by a syringe pump to an injection tube and dispersed into a stream of hydrogen and helium. This vapor was transported into a hot quartz tube reactor. Aligned carbon nanotubes were grown on the carbon fiber surface at680℃.(3) Because of their noticeable mechanical, chemical and physical properties, carbon nanotubes (CNTs) and carbon fibers (CF) are attracted wide attention as reinforcement for composites. However, both of them have poor wettability and absorption with most polymers because their surface is non-polar and compound of highly crystallized graphitic basal planes with inert structures. In order to improve the performance of composites, we used chemical method to modify CNT and CF surface. And after that, the composites’performances were studied. The interfacial bonding strength between fibers and polymer matrices is low, therefore, good mechanical performance of composites cannot be ensured. We use the chemical method and chemical vapor deposition to modify the carbon fiber surface. The morphology of CNT/carbon fibers was examined by scanning electron microscope (SEM). SEM observation revealed uniform coverage of carbon fibers with carbon nanotubes in both of CVD method and chemical method. CNT grafted woven carbon fibers were used to make carbon/epoxy composites and their mechanical properties were measured using three-point bending and tension tests which showed that those with CNT grafted carbon fiber reinforcements using the CVD process has11%higher tensile strength compared to those containing carbon fibers modified with the chemical method. Also, composites with CNT grafted carbon fibers with chemical method showed20%higher tensile strength compared to composites with unmodified carbon fibers. The results of tensile test revealed that both CVD and chemical grafting could significantly improve the mechanical properties of the carbon fiber composites.(4) In the here proposed work we intend to investigate systematically of grafting carbon nanotube (CNTs) and nanocrystal cellulose (NCC) onto carbon fiber surface (CF). The main goal is to make CNTs-NCC-CF using NCC as a bridging molecule between CNT and CF. Grafting secondary materials onto carbon fibers and carbon nanotubes is often limited by the low reactivity of graphitic carbon and there is strong demand to create novel grafting methods using functional groups. One desirable functional group is a carboxylic acid, which strongly interacts with many organic and inorganic materials. Another advantage is that the carboxylic acid group can be modified and also be used as an active group to bind CNT, NCC and CF’s together.(5) Carbon fiber (CF) microwave absorption materials are multifunctional composites with high strength and modulus; good carry capacity, excellent electrical property and reflection loss characteristic, which are increasingly, recognized and practical structural absorption composites. The magnetization modification of carbon fiber is an important way to enhance the microwave absorption property of carbon fiber filled composites. In this paper, a novel environmentally friendly method was proposed for decorating carbon fiber with y-Fe2O3magnetic nanoparticles (maghemite) that aim to develop new functional nanomaterials with good magnetic properties. It was found that excellent uniformity of γ-Fe2O3nanoparticle layers were obtained on carbon materials’ surface. The structure and morphology of the magnetic composites have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), and Raman spectra. The SEM images showed that a complete and uniform y-Fe2O3nanoparticle coating was formed on carbon materials at600℃, and the average diameter of the γ-Fe2O3nanoparticles on the surface was about10nm. The surface properties of y-Fe2O3nanoparticles detached from carbon fibers/γ-Fe2O3composite have been analyzed by XPS and FTIR. The uniformity of y-Fe2O3coating on the surface of carbon materials have improved magnetic and microwave absorption properties of the base materials. This research had great significance for the design and application of microwave absorption materials.