From lignin-derived bio-oil to lignin-g-polyacrylonitrile nanofiber: High lignin substitution ratio and maintaining good nanofiber morphology

In this work, lignin-based nanofibers were produced from corn stalk lignin (CSL)/lignin-derived bio-oil (LBO) and polyacrylonitrile (PAN) co-polymers via electrospinning. During depolymerization , the addition of phosphotungstic acid (PTA) promoted the CSL catalytic conversion to some extent, the decrease of β-O-4 aryl ether bond, molecular weight (Mw) and polydispersity (PDI) was obvious. Compared with CSL, LBO can promotes the formation of uniform and smooth lignin-based nanofibers under high replacement rates condition and maintaining good morphology. Subsequent reactions between LBO and PAN fragments formed a better-integrated co-polymers structure containing linear PAN backbone. The Td of LBO-g-PAN was improved to 153 °C and the Tg was decreased to 96.5 °C. Rheological conclusions displayed that the viscosity of PAN/LBO/DMF was 0.082 Pa s, illustrating the polymer substance could be continuously spun into filament without causing degradation of the polymer substance. LBO-g-PAN also had high thermal stability, yielding of residual mass was 56.32 wt% at 700 °C.