Electrospinning is a process that produces continuous polymer fibers with diameters of a nanometric scale. Nylon 6 in formic acid was electrospun to obtain the nanofibers. Fibers with different diameters were obtained using flow rates of 0.1, 0.5, 1 and 1.5 mL/hr, 20 wt% solution concentration, with an applied voltage of 20 kV and 15 cm spinning distance. Flow rate influenced the fiber diameter distribution, droplet size and its initiating shape at the capillary tip, the trajectory of the jet, maintenance of Taylor cone, areal density and nanofiber morphology. The morphology of the electrospun nanofibers was analyzed by using the scanning electron microscope (SEM). The effect of flow rate on the deposition area was also investigated for better control of the process. It was observed that a stabilized Taylor cone, small average droplet size, narrowest fiber diameter distribution, more stability in the originating jet, and uniform morphology of nanofiber is obtained at a flow rate of 0.5 mL/hr.
Electrospun polyacrylonitrile (PAN) nanofibers were impregnated with KMnO4 under varying conditions of concentration and time. The morphological structures, chemical and thermal properties were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The original and preoxidized samples were stabilized and carbonized for characterization with SEM and FTIR. The coloration, weight gain and solubility in N,N-dimethylformamide were also evaluated. A clear peak at 2340 cm-1 corresponding to MnO4–C=N conjugation, together with a wide peak at 1650 cm-1, was revealed in the FTIR spectrum of the preoxidized samples. Based on the DSC results, the cyclization reactions in the preoxidized samples were accelerated by initiating the exothermic reaction at lower temperatures. The modified samples had higher reaction times and ΔH values, broad exotherms, lower initial induction time and lower Ti values than the untreated ones.
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