Carbohydrates and other impurities presented in the hardwood
lignin have been effectively removed by filtration through ceramic
membrane without breaking the basic structure of lignin. Continuously spooled Lignin/PLA fibers and cylindrically shaped Lignin/
PLA based carbon fibers were prepared by melt spinning of Lignin/
PLA blends followed by the thermal stabilization and carbonization
processes of the Lignin/PLA fibers. The introduction of PLA has
improved the spinnability of the resultant PLA/Lignin blends
compared to that of pure lignin, which would otherwise produce
brittle melt spun fibers. The morphology and the mechanical
properties of both lignin and Lignin/PLA based carbon fibers were
intensively characterized. The volatilization of PLA in the blended
fibers during the thermal stabilization and carbonization processes
leads to voids on the surface and in the cross-section of fibers,
which decreases the tensile strength of Lignin/PLA based carbon
fibers. On the other hand, the tensile modulus of Lignin/PLA based
carbon fibers, up to 11.6 GPa with a Lignin/PLA ration of 80/20, are
much higher than that of pure lignin (1.7 GPa). This increment in
tensile modulus was proposed to be caused by the hydrogenbonding interaction between lignin and PLA phases, which was
characterized by FTIR and DSC. Further work is ongoing to improve
the mechanical properties of obtained carbon fibers by controlling
the porosity formation and optimizing the spinning conditions of
Lignin/PLA blends