Formation and Structure of Sodium Cellulosates in Relation to Physical Properties of Cellulosic Fibers

Abstract

The exchange reaction between sodium methoxide and cellulose, leading to the forma tion of sodium cellulosate, has been studied with respect to the effects of reagent concen tration, temperature, time, nature of the cellulosic substrate, and mechanical constraint. Cellulosate degree-of-substitution values up to 0.6 can be achieved readily in the case of preswollen cotton and rayon yarns. The reaction is complete within a few minutes and no significant effect of temperature above 21°C was observed. The degree of substitu tion increases with increasing sodium methoxide concentration. The distribution of the cellulosate groups was found to be close to a theoretical one, which might be expected upon random substitution. Although highly ionized anhydro glucose units were formed, no redistribution of the cellulosate groups by inter- or intra molecular exchange reactions was observed. Mechanical properties of cotton and rayon yarns which were regenerated from their sodium cellulosate derivatives by hydrolysis were determined, revealing that the formation of a sodium cellulosate derivative did not alter these properties. It was also shown that no chemical degradation of the cellulose occurred during sodium cellulosate formation.