Development of Lignin Carbon Fiber and Reinforced Composites

The aim of this work is to develop lignin carbon fiber for composite applications. This included mechanical testing of single lignin carbon fiber (LCF), interfacial shear strength determination for LCF-resin systems using single fiber fragmentation, x-ray diffraction for the evaluation of microstructural parameters, and finally composite manufacturing and testing. Through these focused areas of analysis, the carbon fiber is thoroughly characterized and composite performance is evaluated. This effort was a collaboration with the Center for Renewable Carbon (CRC) and the Civil and Environmental Engineering Department. LCF produced by the CRC resulted in fibers having tensile strength of 250-800 MPa and Young’s modulus of elasticity of 29-40 GPa. The produced LCF consistently demonstrated superior interfacial shear strength properties when compared with commercially available PAN based carbon fibers. This finding is likely due to the functional groups remaining on the fiber surface because LCF is processed at a lower temperature relative to PAN based carbon fibers and there are fundamental differences in the molecular chemistry and arrangement of the precursor.