Optical anisotropy of concentrated cellulose solutions in N-methylmorpholine N-oxide

Conditions for the appearance of optical anisotropy and supermolecular structure in 20-50% solutions of cellulose in N-methylmorpholine N-oxide at various temperatures were studied by measuring optical transmission in crossed polarizers and small-angle scattering of polarized light. Parameters of anisometric structures (length, diameter, root-mean-square angle of orientational disorder) were determined for both nonoriented and oriented 50% solutions subjected to heating and postdeformation relaxation. Changes in optical anisotropy of cellulose 50% solutions with temperature- and concentration-induced transformations and processes of structural orientation seem to be due to the formation of a mesophase. However, experimental results obtained do not allow unambiguous conclusions on the type of the mesophase for cellulose solutions in N-metlhylmorpholine N-oxide.