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Lin, J., Kubo, S., Yamada, T., Koda, K., and Uraki, Y. (2012). "Chemical thermostabilization for the preparation of carbon fibers from softwood lignin," BioRes. 7(4), 5634-5646.

Abstract

A thermally fusible softwood lignin was directly isolated by a solvolysis of cedar wood chips with a mixture of polyethylene glycol 400 (PEG 400) and sulfuric acid. Its fusibility was found to be due to a PEG moiety introduced into the lignin by the solvolysis. The lignin was easily formed into fibers by melt-spinning at temperatures ranging from 145 to 172 ºC without any modification. The lignin fibers could be converted into infusible fibers as a precursor for carbon fibers (CFs) by conventional oxidative thermal stabilization processing in air or a stream of oxygen for 2 days. We found that the infusible fibers resulted from the partial cleavage of the PEG moiety from the lignin fibers after treatment with 6 M hydrochloric acid at 100 ºC for 2 h. The infusible fibers were converted into CFs with a tensile strength of 450 MPa by carbonization at 1000 ºC under a N2 stream.
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