In conclusion, the tensile strength of present carbon fibers produced from dry-spinning of partially acetylated lignin is amongst the highest values reported in the literature. It is also noted that crenulated carbon fibers obtained in this study from dry-spinning of ACE-SKL have 35% larger surface area as compared with equivalent circular fibers that are typically obtained by melt-spinning. Further, due to the lack of graphitic crystallinity in these lignin-derived carbon fibers, their surface is expected to be more reactive than that of carbon fibers possessing graphitic structure (such as those from mesophase pitch precursor) that tends to be rather inert due to the stable crystalline form. Therefore, such lignin-derived carbon fibers could possess an intrinsically higher fiber–matrix interfacial bond strength when used in polymeric composites.
Acknowledgments
The authors gratefully acknowledge financial support from SERDP WP-1758 (ARL project monitor: Dr. John LaScala). The authors would also like to acknowledge Marlon Morales and Dr. Y.P. Jeon for helping with WAXD and fiber spinning measurements