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.