  Methylcellulose/cellulose nanocrystal (MC/CNC) nanocomposite fibers showing
high ductility and high modulus of toughness were prepared by a simple aqueous
wet-spinning from corresponding nanocomposite hydrogels into ethanol
coagulation bath followed by drying. The hydrogel MC aq. concentration was
maintained at 1 wt-% while the CNC aq. loading was systematically varied in the
range 0 - 3 wt-%. This approach resulted in MC/CNC fiber compositions from
25/75 wt-%/wt-% to 95/5 wt-%/wt-%. The optimal mechanical properties were
achieved with the MC/CNC composition of 80/20 wt-%/wt-% allowing high strain
(36.1 %) and modulus of toughness (48.3 MJ/m^3), still keeping a high strength
(190 MPa). Further, we demonstrate that the continuous spinning of MC/CNC
fibers is potentially possible. The results indicate possibilities to spin
MC-based highly ductile composite fibers from environmentally benign aqueous
solvents.
