Oxidative stabilization of pitch-polyacrylonitrile composite nanofibers electrospun by incorporating high-percentage inexpensive pitch

Polyacrylonitrile (PAN)-based composite nanofibers incorporated with high-percentage inexpensive pitch were successfully prepared by a simple electrospinning technique. Low-softening-point naphthalene pitch (NP) has the merit of high solubility but inevitably brings about preoxidation problem. Thus the influence of different preoxidation strategies on the morphology, composition, and structure of composite nanofibers was systematically investigated. The results show that there exists a ternary phase diagram consisting of PAN-pitch-solvent and a suitable apparent viscosity of homogeneous solution, which favors the smooth electrospinning and good adjustment for the diameter of carbon nanofibers (100-500 nm). The crystallinity, crystalline order, and electrical conduction of composite nanofibers are enhanced by incorporating graphitizable NP, for example, the electrical resistance of 50% NP-PAN composite nanofiber films after 800 degrees C carbonization decreases about 30%. Both increasing the oxidation temperature and extending the oxidation time are beneficial to the oxidative stabilization of composite nanofibers with a suitable NP percentage below 50%. Gradient heating (240-340 degrees C) and pressurized (0.08 MPa) preoxidations could accelerate the oxidative stabilization of composite nanofibers with a high NP percentage up to 110% and significantly shorten the oxidation time by half. Therefore, this study paves the road for facile preparation of cost-competitive carbon nanofibers with controllable morphology, structure, and properties.