Crystalline Investigations of Cellulose Films and Fibers Prepared Using Ionic Liquid Mixed Solvent

Abstract

Cellulose films and fibers were prepared by using an ionic liquid solvent (Tetrabutylammonium acetate / Dimethyl sulfoxide). The characteristics of the films and the fibers were evaluated mainly from the viewpoint of crystallinity. The crystallinity of the films prepared with water as a coagulation solvent showed the highest value, whereas it decreased when other organic solvents were added to the coagulation bath. The diffraction intensity from the (1 1 0)plane, that is a so-called hydrophilic plane of cellulose II crystal, of the water-coagulated film was remarkably high in the X-ray diffraction profiles. It suggested that the surface characteristics of the film can be changed by changing the coagulation solvent. The crystallinity of the films was also affected by the machine speed of film formation and it showed the highest value when the speed was 50 m/min. For the fiber sample, the crystallinity of the obtained fiber increased with the draw ratio (up to 3 times). It also increased with the cellulose concentration of the dope. The cellulose content of the raw material affected the crystallinity and the strength of the obtained fibers. These results can be a guideline for molding films and fibers from cellulosic raw materials through ionic liquids.