UV assisted stabilization routes for carbon fiber precursors produced from melt-processible polyacrylonitrile terpolymer

A low-cost route for producing PAN-based carbon fibers is being developed. The approach involves forming polyacrylonitrile terpolymers that can be melt-spun into fibers. The fibers are then stabilized and carbonized to yield carbon fibers. Melt-processibility, however, precludes direct thermal stabilization of these polymeric fibers. Therefore, a precursor terpolymer containing acryloyl benzophenone (ABP) is used. The UV sensitivity of ABP moiety enhances the UV crosslinkability of the precursor fibers. After a brief exposure to UV radiation, the melt-spun terpolymer fibers can be oxidatively stabilized at 320 °C without melting and subsequently carbonized. UV-visible and ATR-IR spectroscopic analyses suggest that UV radiation induces the formation of free radicals which, in turn, cyclize the PAN. Cyclized PAN was characterized by a strong absorbance in UV-visible region (300-500 nm) due to conjugated >CC< and >CN- bonds which were also detected by infrared spectroscopy.