Flow curves of dense colloidal dispersions: schematic model analysis of the shear-dependent viscosity near the colloidal glass transition

TL;DR

This paper compares a schematic model for the non-linear rheology of dense colloidal dispersions with experimental flow curves of thermosensitive particle suspensions, demonstrating the model's ability to capture key rheological behaviors near the colloidal glass transition.

Contribution

It provides a quantitative analysis showing that the schematic model effectively describes the shear-dependent viscosity and yielding behavior of dense colloidal dispersions, with considerations for hydrodynamic interactions.

Findings

Model captures increase in low shear viscosity with density

Model reproduces shear thinning behavior

Model explains yielding of soft glassy solids

Abstract

A recently proposed schematic model for the non--linear rheology of dense colloidal dispersions is compared to flow curves measured in suspensions that consist of thermosensitive particles. The volume fraction of this purely repulsive model system can be adjusted by changing temperature. Hence, high volume fractions ($\phi \leq 0.63$) can be achieved in a reproducible manner. The quantitative analysis of the flow curves suggests that the theoretical approach captures the increase of the low shear viscosity with increasing density, the shear thinning for increasing shear rate, and the yielding of a soft glassy solid. Variations of the high shear viscosity can be traced back to hydrodynamic interactions which are not contained in the present approach but can be incorporated into the data analysis by an appropriate rescaling.