Effect of aggregation on viscosity of colloidal suspension

This experimental study of viscosity of colloidal suspensions was performed using monodisperse polystyrene latex with particle diameter of 1.15 μm and a pH dependent negative zeta potential of up to 120 mV in aqueous solutions. The range of electrostatic repulsion between the particles was controlled by varying the concentration of potassium chloride. Suspensions under investigation were either in a stable, coagulated, or gelated, state depending on the salt concentration. Shear thinning behaviour was observed for all the samples studied. The dependence of viscosity on shear rate imposed was found to depend substantially on the salt concentration.