Electrospinning of Softwood Organosolv Lignin without Polymer Addition

Due to its nature and structure, lignin is a very difficult polymer to electrospin without any additives as only a few studies reported on the successful electrospinning of lignins in general and even more limited for softwood lignins to date. This paper highlights the possibility to use softwood organosolv lignin as a precursor for fiber electrospinning without any polymer addition. We have successfully electrospun pure organosolv softwood lignin into uniform, bead-free fibers. A concentration of 57 wt % of lignin in dimethyl formamide was determined as optimal, while other processing parameters (voltage, needle–collector distance, flow rate, and humidity) were studied to improve the fiber uniformity. We also studied the effects of minimum FeCl3 addition and demonstrated its efficiency in improving the processability. Thus, the addition of 2 wt % FeCl3 allowed decreasing the minimum fiber diameter from 400 to 200 nm. The addition of FeCl3 also resolved the problem of fiber fusion on the collector, and it also allowed increasing the glass transition temperature of lignin fibers. These results open a way to new applications of lignin, such as 100% biosourced carbon fiber since no petroleum-sourced molecules were used in this study.