EFFECT OF SURFACTANT ON RHEOLOGICAL PROPERTIES OF AQUEOUS TITANIUM-DIOXIDE SUSPENSIONS

The effect of a cationic surfactant on the rheological properties of aqueous TiO2 suspensions was studied by measuring the steady flow and the dynamic elastic properties by varying the surfactant concentration. The rheological properties were correlated with the dispersion stability. It was found that as the surfactant concentration increases, the rheological properties (η, η′, τ, G′, G″) increased initially and then decreased, showing a maximum. As the concentration increased further, the parameters increased, showing a minimum. The rheological parameters reach a maximum and a minimum at the surfactant concentrations at which the stability reaches a minimum and a maximum. The flocculation caused by depletion at high surfactant concentration is more elastic than the flocculation caused by charge neutralization at low surfactant concentration. The long range electrostatic repulsion between particles may be the cause of the elastic properties of the depletion flocculation. © 1992.