The Impact of non-DLVO Forces on the Onset of Shear Thickening of Concentrated Electrically Stabilized Suspensions

TL;DR

This paper extends an activation model to include non-DLVO forces, improving predictions of shear thickening onset in concentrated suspensions by considering force chain percolation and instability before critical stress.

Contribution

The authors introduce an extended activation model incorporating non-DLVO forces and percolation theory to better predict shear thickening behavior in suspensions.

Findings

Inclusion of non-DLVO forces improves prediction accuracy.

The model aligns with experimental data on inorganic oxide suspensions.

Suspension instability occurs before reaching the critical stress predicted by the original model.

Abstract

This paper exposes an extension of an activation model previously published by the authors. When particles arranged along the compression axis of a sheared suspension, they may overcome the electrostatic repulsion and form force chains associated with shear thickening. A percolation based consideration, allows an estimation of the impact of the force chains on a flowing suspension. It suggests that, similar to mode-coupling models, the suspension becomes unstable before the critical stress evaluated from the activation model is reached. The theory is applicable only to discontinuous shear thickening, and the predictions are compared with results from two experimental studies on aqueous suspensions of inorganic oxides; in one of them hydration repulsion and in the other hydrophobic attraction can be expected. It is shown that the incorporation of non-DLVO forces greatly improve predictions of the shear thickening instability.