Development of Solution Spun Bio-Derived Carbon Fiber from Fractionated Lignin

The proposed research focuses on the utilization of lignin as a partial replacement for polyacrylonitrile (PAN) polymer in the spinning of precursors for carbon fiber (CF), in order to produce a bio-derived CF. We propose to overcome lignin issues faced by other researchers by employing a fractionation method. Additionally, our lignin supplier, Valmet, will provide several kilograms of specially formulated lignin with low ash and metals content compared to previously used lignin (BioChoice). We will work to fractionate the lignin, removing the cut soluble in the coagulation bath chemistry, preventing leeching and void formation. The remaining cut will be used to formulate the spinning solution at UKY CAER. Characterization of the soluble and insoluble lignins by Valmet will determine how to better refine the lignin source. During spinning at UKY CAER, the concentration of lignin with respect to PAN will be maximized, while preserving spinnability. A baseline PAN fiber will be spun for comparison. As-spun fiber will then be thermally converted to carbon fiber in a batch process. The resulting CF will be characterized for fiber morphology, density, tensile properties, etc., and compared to the current state of the art, as well as the DOE automotive targets for CF strength and modulus of 1.72 GPa and 172 GPa, respectively.