Water-Soluble Cellulose Derivatives

Abstract

Abstract The effects of temperature and of the presence of acid and alkali on the viscosity of aqueous dispersions of methyl-, methylethyl- and sodium carboxymethylcellulose have been studied. Irreversible viscosity decreases may occur on heating dispersions of all three. The magnitude of the decrease varied with the temperature and time of heating, and with the viscosity grade and type of derivative. The efflux time reductions caused by heat in the presence of acid were greater than in neutral or alkaline dispersions. Viscosity changes may also occur in unheated dispersions in the presence of acid and alkali. The magnitude of the changes was related to the pH value of the dispersion, the time of storage and the nature of the derivative. There were no significant pH changes in the dispersions either on heating or after storage.