Influence of particle concentration on rheological properties of aqueous α-Al 2O 3 suspensions

Abstract

The influence of particle concentration on the rheological properties of aqueous alumina suspensions is investigated under steady and oscillatory shear conditions. At solid volume fractions between 0·45 and 0·6, a high degree of particle stabilization is achieved when 0·2 wt% of polyacrylic acid is added as a dispersant. With increasing particle concentration the flow behavior changes from pseudoplastic to plastic. The apparent yield stress (from the generalized Casson model) is found to be a significant quantity for characterizing changes in structural conditions of the disperse phase with increasing solids loading even though more detailed information is provided by viscoelastic properties. The analysis of viscoelastic data based on the Friedrich–Braun fractional derivative model and the generalized Maxwell model showed that transitions of particle arrangements due to electrostatic repulsion take place at Φ=0·5 and 0·55. For these critical concentrations the influence of latex binder addition on the rheological properties is examined.