Synthesis of electrospun polyacrylonitrile-derived carbon fibers and comparison of properties with bulk form

Abstract

This study deals with the fabrication of polyacrylonitrile (PAN) nanofibers via an electrospinning process followed by stabilizing and carbonization in order to remove all non-carboneous matter and ensure a pure carboneous material. The as-spun PAN fibers were stabilized in air at 270 degrees C for one hour and then carbonized at 750, 850, and 950 degrees C in an inert atmosphere (argon) for another one hour. Differential scanning calorimetry and Raman spectroscopy were employed to determine the thermal and chemical properties of PAN. Surface features and morphologies of PAN-derived carbon nanofibers were investigated by means of scanning electron microscopy (SEM). SEM micrograms showed that fiber diameters were reduced after carbonization due to evolution of toxic gases and dehydrogenation. The Raman spectra of carbonized fibers manifested D/G peaks. The Raman spectroscopy peaks of 1100 and 500 cm(-1) manifested the formation of y phase and another peak at 900 cm manifested the formation of a-phase. The water contact angle measurement of carbonized PAN fibers indicated that the nanofibers were superhydrophobic (theta > 150 degrees) due to the formation of bumpy and pitted surface after carbonization. In DSC experiment, the stabilized fibers showed a broad exothermic peak at 308 degrees C due to cyclization process. The mechanical and Thermal analysis was used to ascertain mechanical properties of carbonized PAN fibers. PAN-derived carbon nanofibers possess excellent physica and mechanical properties and therefore, they may be suitable for many industrial applications such as energy, biomedical, and aerospace.