(695a) UV-Assisted Stabilization of Modified Softwood Kraft Lignin Fibers

Production of high strength carbon fibers from bio-derived precursors is of topical interest.  Carbon fibers were produced from a partially acetylated softwood kraft lignin, but the thermo-oxidative stabilization required a low heating rate below 0.2°C/min to prevent the fibers from being heated too rapidly and becoming soft / tacky. Therefore, in this study, stretched as-spun fibers were UV irradiated for 15 min.  The fibers underwent sufficient crosslinking on the surface such that they could be subsequently thermally stabilized at heating rate as high as 1.4°C/min. The extent of reaction was studied using FTIR, and the glass transition temperature evolution was assessed by DSC. Stabilized fibers were successfully carbonized at 1000°C, and resulting carbon fibers displayed a tensile strength as high as 1 GPa. These results establish that UV irradiation can effectively shorten the total stabilization time for lignin-based carbon fibers.