Fiber formation from liquid-crystalline precursors. II. Cellulose in N,N-dimethylacetamide-lithium chloride

Fibers were spun from isotropic and biphasic solutions of regenerated cellulose (DP = 290) in N, N‐dimethylacetamide +7.8% LiCl using water as a coagulant. There is an increase in mechanical properties through the isotropic → anisotropic transition with moduli reaching 22 GPa. The problem with this system is that crystallization encroaches on the biphasic region, and a pure mesophase is never observed. However, owing to the slow nucleation rate of the crystals, a biphasic solution is stable for a long time and can be spun to yield high modulus and orientation. The best approach is to use small flow gradients (extrusion rate and pick‐up ratio) and to allow long times for homogenization and nucleation of the mesophase.