(769f) Carbon Fibers Derived from Fractionated-Solvated Lignin Precursor

Jin, J., Clemson University
Klett, A. S., Clemson University
Ding, J., Clemson University
Thies, M. C., Clemson University
Ogale, A. A., Clemson University
Carbon fibers (CFs) possess outstanding specific strength and modulus. Therefore, they are used commercially in structural composite applications (viz. aerospace) for enhanced performance and fuel efficiency, resulting from superior strength-to-weight ratio. The vast majority of commercial CFs are currently produced from a synthetic precursor polyacrylonitrile (PAN) via wet-spinning. The cost of PAN precursor not only contributes to about 50% of CF costs, but the nitrile groups generate toxic by-products (viz. hydrogen cyanide) during heat-treatment. Thus, bio-derived CF precursors are of increasing interest from an environmental perspective. Among renewable feedstocks, lignin is an important potential precursor for carbon fibers [1,2]. Although lignin is readily available as an inexpensive by-product, it is too high in metal impurities. Therefore, a renewable solvent system consisting of hot-acetic acid-water mixture has been developed to purify, fractionate, and solvate kraft lignins [3,4]. Using different molecular weight fractions of the solvated lignin, direct dry-spinning of lignin precursor fibers was accomplished, followed by their conversion to carbon fibers. The resulting CFs possessed a tensile strength of 1.3±0.3 GPa and modulus of 86±8.8 GPa, and represents the highest combination of strength and modulus of CFs derived from lignin.

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