STUDIES ON CARRAGEENIN: THE EFFECT OF SHEAR RATE ON VISCOSITY

Abstract

The viscosity of aqueous solutions of carrageenin of high molecular weight was markedly dependent on the rate of shear. The shear-dependence increased with decrease in the concentration of added electrolyte. Because of curvature, extrapolation of [η] to zero rate of shear was not possible. The Huggins interaction coefficient, k′, increased with decrease in rate of shear; k′ also increased with increase in concentration of added electrolyte. In water, maxima of η_sp/c were observed at concentrations of carrageenin equivalent to the ionic impurities in the distilled water used. At higher concentrations the data fitted the Fuoss equation at rates of shear of 200 and 100 sec.⁻¹ but not below 100 sec.⁻¹ The constants A and D both increased with decrease in rate of shear.