The plasticized spinning and cyclization behaviors of functionalized carbon nanotube/polyacrylonitrile fibers
The plasticized spinning and cyclization behaviors of polyacrylonitrile (PAN) and polyacrylonitrile/functionalized carbon nanotube (PAN/CNT-COOH) composite fibers were studied. The PAN/CNT-COOH fibers containing 0.8 wt% CNTs exhibit excellent tensile strength and modulus, i.e. 0.475 GPa and 10.93 GPa, which are 69.6% and 40.13% improvement respectively, compared to their precursor fibers. The changing trend of crystallinity of PAN/CNT-COOH fibers is associated with the heat exchange rate and oriented-crystallization rate, which can be confirmed by the X-ray diffraction (XRD) results. The cyclization behaviors of the fibers were examined using X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that cyclization of PAN/CNT-COOH fibers is initiated by three types of initiating agents, i.e., modified CNTs (CNTs-COOH), oxygen containing groups generated during the plasticized spinning and comonomers. Meanwhile, the PAN/CNT-COOH fibers exhibit various cyclization behaviors induced by high spinning speeds.