Investigation of the behavior of unstable colloidal dispersions under shear

The aim of this project is to investigate the behavior of unstable colloidal dispersions in the presence of shear forces by means of Stokesian Dynamic simulations.

Colloidal suspensions are very often exposed to shear forces during processing. While under certain conditions it is imperative that the particles remain colloidally stable under shear, in other cases shear forces are used to induce or accelerate their coagulation. Therefore, understanding the relevance of colloidal interactions and their interplay with hydrodynamic forces is of great importance. In order to investigate conditions relevant to real-life systems, concentrated colloidal dispersions need to be considered.  The objective of this work is to make use of simulations to clarify the behavior of concentrated colloidal dispersions with low colloidal stability under shear. Stokesian dynamics is the technique used to model the time evolution of the colloidal dispersions accounting for hydrodynamic interactions, and also permits to compute the evolution of rheological properties of the dispersion. Two situations are explicitly considered. The first one considers the behavior of colloidal dispersion with either no or low repulsive interactions among the particles under simple shear conditions. The goal is primarily to find which conditions lead to the formation of colloidal gels. The second subproject studies the behavior of colloidal clusters exposed to shear conditions in order to assess the role played by interparticle interactions on their breakage behavior.

Involved people

Adolphe Merkle Institute - Chemin des Verdiers 4 - CH-1700 Fribourg - Phone +41 26 300 9254