EFFECT OF SHEAR RATE ON THE VISCOSITY OF SOLUTIONS OF SODIUM CARBOXYMETHYLCELLULOSE AND K-CARRAGEENAN

The apparent viscosities of aqueous solutions of sodium carboxymethylcellulose (NaCMC) and k‐carrageenan have been measured over a range of shear rates from 14 to 1142 s−1. Comparable measurements were also made on gum solutions to which glucose, sucrose, or glucose syrup had been added. For all the solutions the variation of relative viscosity with shear rate fits a power law equation. Addition of sugars to the most concentrated solutions of NaCMC has no effect on the non‐Newtonian behaviour but addition of glucose syrup to the most dilute solutions of NaCMC decreased the non‐Newtonian behaviour. However, the general pattern of behaviour showed close similarity with that of guar gum and locust bean gum. In the more concentrated glucose and sucrose solutions the non‐Newtonian behaviour of k‐carrageenan was increased appreciably. There was no comparable effect on k‐carrageenan in glucose syrup solutions. This different behaviour of k‐carrageenan is attributed to the development of solute‐solute interactions. Copyright © 1979 John Wiley & Sons, Ltd