Thermal gelation properties of carboxymethyl cellulose and bentonite carboxymethyl cellulose dispersions: Rheological considerations
Abstract The aim of this work was to study the thermal behavior of carboxymethyl cellulose (CMC) aqueous solutions and bentonite CMC mixtures, from room temperature to higher temperatures, above gelation, using a rheological analysis. The rheological properties of aqueous CMC solutions and bentonite CMC dispersions at different mass concentrations of CMC (0.1, 0.5, 1.0 and 2.0 wt% were investigated at different temperatures (20, 40, 60 and 80 degC) using large deformation rheological measurements. Viscosity measurements show that for both CMC solutions and bentonite CMC dispersions sudden changes in viscosity occur as the temperature increases. The viscosity is found to decrease below a critical temperature which corresponds to a cloud point or gelation temperature. Above this later, the viscosity increases dramatically with temperature. Hydrophobic interaction is postulated to be the cause of gelation.