THE RHEOLOGY OF A STERICALLY STABILIZED SUSPENSION AT HIGH-CONCENTRATION

The theology of a model soft-sphere suspension is studied and compared with that of a model hard-sphere suspension. Particular emphasis is placed on observing the transition from liquid-like to solid-like behavior at the maximum packing volume fraction, γm. At concentrations below γm the rheological properties of the soft-sphere suspension, measured using capillary viscometry, steady shear, and oscillatory shear, are similar to those of the hard-sphere suspension, and the two sets of data can be scaled using a reduced volume fraction, γ γm. As the volume fraction approaches γm, the behavior changes rapidly from viscous Newtonian to viscoelastic shear thinning. Above γm elastic solid-like behavior is observed and a yield stress can be measured. However, the volume fraction scaling with the hard-sphere suspension breaks down, with the yield stress and oscillatory properties of the soft-sphere suspension increasing more rapidly with concentration. © 1992.