Strengthening of polyacrylonitrile (PAN) fiber networks with polyamide epichlorohydrin (PAE) resin

Polyacrylonitrile (PAN) fibers are one of the most important synthetic fibers that are widely studied because of their excellent characteristics, such as good mechanical strength, chemical resistance, and good thermal stability. Polyamide epichlorohydrin resin (PAE) is a type of cross-linking strengthening resins, with abundant active groups. However, the strengthening mechanism of polyamide epichlorohydrin resin (PAE) in synthetic fiber sheet is not clear. Herein, to meet the feasibility of some synthetic fiber sheet application, PAE resin reinforced polyacrylonitrile (PAN) fiber networks (PAE/PAN hybrid networks) were successfully prepared. Fourier transform infrared spectroscopy-attenuated total reflection (FTIRATR) spectroscopic and X-ray photoelectron spectroscopy (XPS) were used to characterize the self-cross-linking process which the formation of tertiary amine group in PAE/PAN hybrid networks boosted by the self-crosslinking of PAE polymer. The hot-pressing conditions, like temperature, time, and pressure, were also optimized. By adding low amount (0.6 wt%) of PAE serving as cross linkers, the density, tensile index, tear index, and elongation were increased by 9.6, 21.0, 25.8, and 34.3%, respectively. This work suggests a promising PAN fiber enhancement strategy with outstanding mechanical properties by adding PAE resin used as excellent self-cross-linking material and may have great practical application prospects in some other synthetic fiber sheets.