Shear Thickening in Concentrated Soft Sphere Colloidal Suspensions: A Shear Induced Phase Transition

TL;DR

This paper presents a theoretical model explaining shear thickening in dense soft sphere colloidal suspensions as a shear-induced phase transition, supported by experimental validation.

Contribution

It introduces a Landau model incorporating coupling between fluctuations and strain to describe shear thickening as a phase transition.

Findings

Critical shear stress derived for shear thickening.

Reversible and irreversible shear thickening share the same origin.

Model confirmed by experimental data on stabilized colloids.

Abstract

A model of shear thickening in dense suspensions of Brownian soft sphere colloidal particles is established. It suggests that shear thickening in soft sphere suspensions can be interpreted as a shear induced phase transition. Based on a Landau model of the coagulation transition of stabilized colloidal particles, taking the coupling between order parameter fluctuations and the local strain-field into account, the model suggests the occurrence of clusters of coagulated particles (subcritical bubbles) by applying a continuous shear perturbation.The critical shear stress of shear thickening in soft sphere suspensions is derived while reversible shear thickening and irreversible shear thickening have the same origin. The comparison of the theory with an experimental investigation of electrically stabilized colloidal suspensions confirms the presented approach.