Polarized Optical Microscopy of Cellulose/Poly(vinyl alcohol) Blend Gel Fibers.

Abstract

Cellulose/poly (vinyl alcohol) (PVA) blend gel fibers were prepared by extrusion of the blend solutions in N, N-dimethylacetamide-LiCl from tubular flow field into methanol. Influences of PVA content and flow on the macroscopic orientation of cellulose in the gel fibers were examined by polarized optical microcscopy. Cellulose chains had a strong tendency to orient parallel to the gel wall. The degree of the chain orientation was much lowered with increasing PVA content. Under the lowest flow rate, with increasing PVA content, the orientational distribution deviated from longitudinal to circumferential direction. These results were attributed to influences of the interactions between the two polymers. Under the higher flow rate, all the resultant gels exhibited the larger die swell with the latter type of orientational deviation. From the observation of a PVA gel phase which remained after the treatment with the enzyme, most of PVA chains were deduced to exist as amorphous chains in the blend gel fibers.