Lignin-based carbon fibers: Effect of synthetic polymer blending on fiber properties

Carbon fibers have been produced from hardwood lignin/ synthetic polymer blend fibers. Hardwood kraft lignin was thermally blended with two recyclable polymers, poly( ethylene terephthalate) ( PET) and polypropylene ( PP). Both systems were easily spun into fibers. A thermostabilization step was utilized prior to carbonization to prevent fusion of individual fibers. For the lignin-based carbon fibers, careful control of heating rate was required. However, PET-lignin blend. bers can be thermostabilized under higher heating rates than the corresponding homofibers. Carbon fiber yield decreased with increasing incorporation of synthetic plastic. However, carbon fiber yield obtained for a 25% plastic blend fiber was still higher than that generally reported for petroleum pitch. Blend composition also affected surface morphology of the carbon. bers. Immiscible lignin - PP. bers resulted in a hollow and/ or porous carbon fiber; whereas carbon fiber produced from miscible lignin - PET. bers have a smooth surface. Synthetic polymer blending also affected the mechanical properties of the. bers, especially MOE; lignin-based carbon fiber properties improved upon blending with PET.