Effect of KMnO4 on chemical, crystal and microscopic structure of polyacrylonitrile fibers

The effects of modification temperature and time on polyacrylonitrile (PAN) fibers under various concentrations of KMnO 4 were studied. Wettability , colouration, chemical structure (Fourier transform infrared spectroscopy), crystal structure (X-ray diffraction), stack domains (D), interlayer spacing (d), microscopic structure (Scanning electron microscopy) and elemental content (energy dispersive spectroscopy) were analysed. Aside from its good hydrophilicity, KMnO 4 at 2 and 4 wt% are beneficial to the modification of PAN fibers. The colouration of the fiber at 80 °C is the most obvious. The clear peak of the pre-oxidised fibers at 2340 cm −1 corresponds to the conjugated structure of MnO 4 –C N. At 4 wt%, the degree of pre-oxidation is too high and the main infrared peak disappears. M 2, 30 has a minimum D of 9.320 nm and 8.258 nm at 2θ = 16.883° and 2θ = 29.673°, respectively, and the fiber crystals are the finest. At a content of 4 wt%, the fibers are axially cracked and crystals appear on the surface. M 2, 30 and M 2, 60 have a close percentage of C element, whereas M 2, 30 has a lower percentage of Mn element. The best modification conditions of KMnO 4 are 2 wt%, 80 °C and 30 min.