Effects of Stabilization Temperature on Structures and Properties of Polyacrylonitrile (PAN)-Based Stabilized Electrospun Nanofiber Mats

An improved heat treatment strategy for electrospun polyacrylonitrile (PAN)-based nanofiber mats is developed. Polyacrylonitrile nanofiber mats were fabricated by electrospining and then were stabilized at different temperatures. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and mechanical testing were used to study the effects of temperature (for times of 1 h) on the structures and properties of PAN-based heat stabilized electrospun nanofiber mats. Results showed that at temperature below 250 degrees C, the structure conversion of PAN nanofibers was not obvious. However, when the stabilization temperature was above 260 degrees C, PAN nanofibers became thermally stable and the aromatization indices increased rapidly to 55.8%, which is preferable for stabilized PAN nanofiber mats. After thermal treatment up to 270 degrees C, most of the C N groups in PAN macromolecules change to C=N groups, implying that the cycling reaction was almost complete at 270 degrees C. The tensile strength of the nanofiber mats revealed that for the highest mechanical properties of the nanofiber mats, the stabilization temperature should be around 260 degrees C.