Steady shear flow properties of Cordia myxa leaf gum as a function of concentration and temperature

Abstract

The steady shear flow properties of dispersions of Cordia myxa leaf gum (CMLG) were determined as a function of concentration (0.5–2.5%, w/w), and temperature (10–50°C). The CMLG dispersions exhibited strong shear-thinning behavior at all concentrations and temperatures. The Power-law (Ostwald–Waele's) and Herschel–Bulkley models were employed to characterize flow behavior of CMLG solutions at 0.1–100s−1 shear rate. Non-Newtonian shear-thinning behavior was observed at all temperatures and concentrations. While increase in temperature decreased the viscosity and increased the flow behavior indices, adverse effect was obtained by increasing the concentration. The Power-law model was found the best model to describe steady shear flow behavior of CMLG. The pseudoplasticity of CMLG increased markedly with concentration. An Arrhenius-type model was also used to describe the effect of temperature. The activation energy (Ea) appeared in the range of 5.972–18.104kJ/mol, as concentration increased from 0.5% to 2.5%, at a shear rate of 10s−1.