Yielding in colloidal gels: from local structure to meso-scale strand breakage and macroscopic failure

TL;DR

This study investigates the microscopic and mesoscopic mechanisms of yielding in colloidal gels under shear stress, revealing how strand breakage leads to macroscopic flow and failure.

Contribution

It provides a multiscale analysis linking local strand breakage to macroscopic flow behavior and introduces a predictive framework for strand failure in colloidal gels.

Findings

Breakage events are homogeneously distributed, indicating ductile flow.

Strand breakage is statistically predictable based on structural and mechanical metrics.

A viscosity bifurcation is demonstrated, connecting microscale dynamics to macroscopic rheology.

Abstract

We study creep flow and yielding of particulate depletion gels under constant shear stress, combining data on different length and time scales. We characterise the breakage of meso-scale strands in the gel. Breakage events are distributed homogeneously in space, corresponding to macroscopically ductile flow. At the microscale, a spatio-temporal analysis of structural and mechanical metrics connects properties of strands before and after they fail, indicating that strand breakage is statistically predictable. Using results from different scales, we discuss the interplay between creeping and aging dynamics, and we demonstrate a viscosity bifurcation.