Structure and Mechanical Properties of Regenerated Cellulose Fibers Wet-Spun from Ionic Liquid/Cosolvent Systems

Cellulose fibers were wet spun from cellulose/ionic liquid (IL)/cosolvent solutions. The cosolvent system was consisting of 1-Ethyl-3-methylimidazolium acetate (EmimAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and water with various composition. Rheological properties of the cellulose/EmimAc with cosolvent solutions showed that dissolution rate can be increased by cosolvent addition, and the complex viscosity can be reduced. The solutions were stable over time at room temperature and could be converted to regenerated fibers with good properties via conventional wet spinning process. The increase in crystallinity of the regenerated cellulose fibers obtained from the EmimAc/cosolvent solution was ascribed to the ability of cosolvent to promote interaction between cellulose chains. The crystallinity of the fibers with only EmimAc as solvent is lower than that of the fibers with cosolvent, it seems that in this case the crystallinity dose reflects the difference in tensile properties. Also, a slight increase in tensile strain, by adding cosolvent to the cellulose/IL system under same wet spinning conditions was observed. The increase in the strain may be due to the crystal chain slip and plasticization effect by the cosolvent dispersed in the fiber, resulting in the increase the mobility of cellulose chain.