Steady-shear flow of semidilute guar gum solutions with sucrose, glucose and sodium chloride at different temperatures

Steady-shear flow curves of aqueous solutions of guar gum at 0.22% at different temperatures (5–65 °C), guar gum (0.22%) with sugars (sucrose or glucose) at different sugar/water ratio (0.10, 0.20 and 0.40) at 5 °C, guar–sugar (at 0.40 sugar/water ratio) at different temperatures (5–65 °C) and guar gum and guar–sucrose (0.40 sucrose/water ratio) with NaCl (1%) at 5 °C, were determined using a controlled-stress rheometer over a wide range of shear rate (1–1000 s−1). Apparent viscosity increased with decreasing temperature and increasing sugar content independent of sugar type. Synergic effect on apparent viscosity due to sugar addition was found and was correlated with sugar content. Salt addition decreased slightly the apparent viscosity and increased the shear-thinning behaviour of the guar gum solution. Steady-shear flow curves were satisfactorily described by the Cross model. Semi-empirical correlations of Cross model parameters with sugar content and temperature were obtained.

► Synergic effects on viscosity of guar solutions with sugar addition are observed.
► NaCl decreases zero-shear viscosity and varies shear-thinning character of solutions.
► Cross model parameters were satisfactorily correlated with temperature.
► Energy of activation values for viscous flow increases with the presence of sugars.