Effects of ultraviolet irradiation on stabilization of textile-grade polyacrylonitrile fibers without photo-initiator for preparing carbon fibers
The ultraviolet (UV) was irradiated on textile-grade polyacrylonitrile (PAN) fibers without photo-initiators to demonstrate the effective stabilization for preparing carbon fibers (CFs). The irradiation for as short as 20 min at 75 °C generated radicals in the textile-grade PAN fibers, which accelerate stabilization, resulting in significant reduction of process time. In addition, stepwise irradiations from 75 to 200 °C by increasing UV power, and following thermal treatments to mimic continuous stabilization for 30 min total provided CFs with tensile strength and modulus of 2.43 ± 0.4 and 195 ± 8.6 GPa. Considering conventional thermal stabilization for at least 60 min and 5 h with special and textile PAN fibers, respectively, the incorporation of UV irradiation into the present system could effectively advance stabilization process to shorten duration and to produce low-cost CFs based on textile-grade PAN fibers as one of cheap precursors.