The Basic Study On Polyacrylonitrile/Carbon Fiber Reinforced By Chitosan Treated Carbon Nanotube

As a special fiber, Carbon fiber in addition to its high strength, high modulus, heat resistance, chemical corrosion, abrasion, electrical conductivity, thermal conductivity, anti-radiation, sound damping, shock absorption, noise reduction properties, also has the flexibility and weaving. That making it widely used in the fields of aerospace, national defense and military. However, the huge amounts of defects confine the mechanical properties which much lower than the theoretical value. Because of its special structure, the original wire, carbon nanotube is a very good reinforce materials of precursor fibers and carbon fibers. Prepare the high-performance fibers of CNTs/PAN via gel-spinning could obtain the high fiber orientation, mechanical properties, and less fiber structural defects PAN precursor fiber. Lay the solid foundation of the preparation of PAN-based carbon fiber.However, for its insoluble, non-melt and tangles easily manipulated reunion, the CNTs hard to homodisperse in CNTs/polymer composite matrix. Those phenomenons weaken and reduce the reinforcement of carbon nanotubes to the composite fibers.This paper first present the method of surface treatment of carbon nanotubes, the dispersion stability of carbon nanotubes treated by different surface treatment methods in organic solvents such as DMF, DMSO, NMP and so on. In this paper, the surface treatment in addition to the traditional surface carboxyl, but also innovative prepare the carbon nanotubes microcapsule by chitosan derivatives which could be dispersed in organic solvents. And then characterize the concentration of carbon nanotube in the solvent by UV-vis spectrophotometer and establish the standard concentration curve. The result shows that: compare to the carbon nanotubes with surface acidification and without treated, the ones which is treated by Phthalonitrile Chitosan (PhthCS), benzoyl chitosan (BCS), naphthyl chitosan (NCS) in the polarity of solvent in 6～10 the solvent dispersion and duration have significantly improved. Through processing, high molecular weight chitosan derivatives coated the surface of the carbon nanotubes as a membrane. Compared to untreated carbon nanotubes, the dispersion of CNTs which is deal with 0.5mg/mL chitosan solution the concentration in organic solvent raised from 1.20mg/mL to 1.83mg/mL.Secondly, swelling the high molecular weight PAN in the spinning liquid with carbon nanotubes 6 hours. And then prepared the CNTs/PAN precursor fibers by gel-spinning. This paper study the effect for the mechanical properties of different ratio of carbon nanotubes and different spinning process. And through SEM the micro-structure of fibers have the carbon nanotubes uniformly in the fiber orientation distribution. Study shows that: in the mass fraction of carbon nanotubes by adding 0.5%, the PAN fiber has the best mechanical properties.Finally, pre-oxidation and carbonization the PAN precursors. We studied the pre-oxidation process conditions, and obtained for the tensile strength and micro-structure of carbon fibers. The result shows that: the addition of carbon nanotubes could effectively improve the mechanical properties of carbon fiber.