High-Quality Carbon Nanofiber-Based Chemically Preoxidized Electrospun Nanofiber

Abstract

Electrospun polyacrylonitrile (PAN) nanofibers were pre-oxidized under 1, 2, and 3 wt% of KMnO4 aqueous solutions. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy were used to study the effect of KMnO4 concentration on the structures and properties of PAN-based heat stabilized and carbonized electrospun nanofiber mats. In FT-IR spectra of the preoxidized samples a new peak at 2340 cm−1 designated to MnO4–C=N conjugation was revealed. Chemical modification by KMnO4 was used to decrease the average diameter, increase the Bragg spacing, and decrease the preferred orientation and the crystal size. According to the Raman spectra, the bandwidths of the G mode became wider in the cases of preoxidized samples, while the G mode intensities belonging to the crystalline regions were decreased. According to the TGA studies, the weight losses in the preoxidized samples were severe due to the permanganate attack.