(490c) Effect of Polyethylene Terephthalate in Producing Carbon Fiber from Pyrolytic Lignin

Pyrolytic lignin is a mixture of lignin-derived phenolic monomers and oligomers. Our previous study showed that repolymerized pyrolytic lignin could be used as a precursor to produce carbon fiber with enhanced mechanical properties. In the present work, pyrolytic lignin was mixed with different ratios of polyethylene terephthalate (PET) to extend the chain length of the precursor and control the molecular orientation. The FTIR spectra of the pyrolytic lignin and PET treated together at 200 ^oC were significantly different from the spectra of the physical mixture of individually treated pyrolytic lignin and PET, suggesting pyrolytic lignin and PET chemically reacted to form a new polymer structure. It is likely that pyrolytic lignin first caused chain scission of PET at the low temperature and then attached to the PET backbone through reacting with the carboxylic acid and vinyl groups on the PET fragments. The new precursors were further characterized using GPC, DSC, TGA, CHN and rheology analysis. The TGA analysis has shown that mixing pyrolytic lignin with 5% of PET increases carbon residue upon heating, thus potentially improving carbon fiber yield. The precursors were subjected to melt-spun at 200 ~ 210 ^oC and the spun fibers were oxidatively stabilized from room temperature to 250 ^oC using a heating rate of 0.3 ^oC/min. Subsequently, the stabilized fibers were carbonized at 1000 ^oC under inert environment. The produced carbon fibers were further characterized for mechanical properties and morphology.