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.

Keywords:

• electrospun PAN nanofiber
• potassium permanganate
• Impregnation
• Raman
• XRD
• carbon nanofiber