The Study Of Surface Modification Of Aramid Fiber And Its Properties

Aramid fiber is a high performance synthetic fiber. The benzene rings arrange alternately in its molecular. It has a rigid rod-like molecular chain, an internal height of orientation and crystallization. All of these structures give the fiber excellent resistance, high strength, flame retardant, corrosion resistance and low coefficient of expansion etc. Therefore, aramid fibers are widely used as high-performance structural and functional materials. However, it is just due to the regular structure that results in the poor surface properties of Kevlar itself, which greatly limits the range of applications of aramid fibers. In order to make full use of the excellent properties of aramid fibers and expand its applications, we need to modify the surface of aramid fibers.In this article, we selected a biomimetic material, dopamine as the surface modifier, and got PPTA@PDOPA through pulling method. At the same time, we explored the main two factors, the concentration of dopamine and the number of puling. The article characterized chemical composition, crystal structure, thermal stability, microscope surface topography, wettability and mechanical properties of the PPTA before and after modification through infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, TGA, SEM, contact angle and the breaking strength test. The results showed that the surface of modified PPTA coated with an active layer of poly-dopamine, the active functional group-amino group and a hydroxyl group increased, the water contact angle reduced from 143.50°to 120.6°with great hydrophilic enhancement; The crystal structure, thermal stability and mechanical properties of modified PPTA stayed the same as the untreated fibers. It’s found that the active layer gradually densified with the increasing of the concentration of dopamine and the number of pulling, and finally we got an conclusion that the optimum experiment condition is 2 g/L of dopamine concentration, 15 times of pulling.Next, based on the obtained active modified PPTA@PDOPA fiber, we prepared conductive aramid fibers through silver plating. Also we use infrared spectroscopy, X-ray diffraction, TGA, SEM, line resistance and breaking strength to characterize chemical composition, crystallization structure, thermal stability, morphology, electrical and mechanical proprieties of conductive PPTA. It’s found that the crystallization structure, thermal stability and mechanical properties remain unchanged, but the surface of PPTA fibers is coated with a layer of dense continuous silver which greatly improved the conductive property of the fibers. The line resistance can reach 0.03?/cm. It also explored the effect factor of silver plating, finally reach to a conclusion: the concentration of AgNO3 at 20g/L, the concentration of C6H12O6 at 20g/L, the time at 25 min.We introduced Twister CW01 and perforated glass tank to simulate industrial continuous production of conductive PPTA fibers. We explored the continuous condition and finally got the optimal conditions: wheel speed at 20r/min, walking distance S at 24 m.