Thermal properties and thermal stabilization of lignosulfonate-acrylonitrile-itaconic acid terpolymer for preparation of carbon fiber

Lignin, the most abundant aromatic biopolymer on the earth, is considered as a sustainable carbon fiber precursor. However, lignin-based carbon fibers face great challenges in the fiber spinning and thermal stabilization due to the complex structure of lignin. In this work, lignosulfonate-acrylonitrile-itaconic acid (LS-AN-IA) terpolymer with excellent spinnability was prepared as a novel precursor for carbon fibers, and the thermal properties and thermal stabilization of this precursor were studied. The introduced itaconic acid (IA) comonomer was found to play an important role in improving the thermal properties and promoting the thermal stabilization. The hindering effect of LS on the cyclization reaction of nitrile groups was overcome by the IA comonomer through changing free-radical reaction mechanism to an ionic one. The thermal stabilization of the LS-AN-IA terpolymer precursor fibers could be carried out at a lower temperature and required a shorter time, which helped to reduce the energy and time consumption. Carbon fibers with tensile strength and tensile modulus of 1.74 GPa and 210 GPa, respectively, were obtained from the LS-AN-IA terpolymer.