Rheology of colloidal BaTiO3 suspension with ammonium polyacrylate as a dispersant

The rheological behavior of barium titanate (BaTiO3) with ammonium polyacrylate (NH4PA) as a dispersant has been investigated over a range of volumetric solids concentration (φ=0.1–0.55) in shear rate 1–1000 s−1. The addition of NH4PA decreased the suspension viscosity pronouncedly. The relative viscosity (ηr) of the suspension defined as the suspension viscosity over the viscosity of the suspending medium was found increasing substantially when φ exceeds 0.4. A derivative of ηr, i.e. 1−ηr−1/2, appeared linearly proportional to φ; from which, a maximum solids fraction (φm) which presents the theoretical solids concentration at which the suspension viscosity approaches infinity was determined as φm=0.584 for the given suspension system. The ηr–φ relationship determined experimentally was compared with various existing models and the (viscosity) predictive capability of the models also discussed.