Preparation of carbon fibers from softwood lignin by atmospheric acetic acid pulping

Infusible softwood acetic acid lignin (SAL) was converted to a Fusible one as a raw material for carbon fibers by removing the infusible high molecular mass fraction-The resulting low molecular mass fraction (SAL-L) was spun by fusion spinning after thermal treatment to remove volatile materials. Carbon fibers (CFs) were prepared From these fibers by direct carbonization without thermostabilization, leading to reduction of the production costs. The tensile strength of SAL-L CFs increased with decreasing diameter, and those of the fine SAL-L CFs were comparable to those of other lignin based CFs such as phenolated exploded lignin. Therefore, SAL-L CFs were classified into general performance grade. (C) 1998 Elsevier Science Ltd. All rights reserved.