Significant progress on understanding the link between microscopic, colloidal and molecular level forces, and bulk dispersion rheology has been achieved. The work to date has focused on providing experimental evidence for the influence of excluded volume (i.e. hard-sphere), electrostatic repulsion, dispersion attraction, and steric stabilization (i.e. polymer) forces on shear thickening. Predictive scaling models for the onset of shear thickening were proposed and validated against quality experimental data.

In this presentation, a derivation is presented of a more rigorous scaling analysis of the basic equations of motion to derive predictive expressions for the onset of shear thickening in concentrated colloidal dispersions. The results of this analysis are validated by comparison to experimental data obtained from our laboratory and the literature. The analysis permits accurate, and robust predictions of the onset of shear thickening in colloidal dispersions. In fact, the analysis enables using experimental measurement of the onset of shear thickening as a probe of the short-range colloidal forces stabilizing dispersions. The analysis also defines the colloidal-level system parameters that should be quantified in order to engineer and formulate dispersions to avoid or control shear thickening.