Viscosity-temperature relationships for dilute solutions of cellulose derivatives: I. Temperature dependence of solution viscosities of ethyl cellulose

Abstract

Viscosities of dilute solutions of six fractions of ethyl cellulose, molecular weight range 40,000–140,000, in six solvents have been determined at different temperatures between 25° and 60°C. Log η is very approximately a linear function of the reciprocal of the absolute temperature T. Values of Q and A in the expression η = Ae Q RT are obtained. The apparent activation energy of viscous flow, Q, is linearly related to concentration c and molecular weight M by Q = Q 0 + K e Mc and A = A 0 e − K a M α c where Q 0 and A 0 are values for the pure solvents and K e , K a , and α are constants for a particular ethyl cellulose-solvent system. The values of K a and α may vary slightly with M. An expression is derived giving the intrinsic viscosity in terms of K e , K a , α, M, and T.