Shear banding phenomena in a Laponite suspension

TL;DR

This study investigates shear banding in a Laponite suspension using dynamic light scattering, revealing gel-like arrested dynamics and stick-slip flow oscillations during shear localization, contributing to understanding soft glassy material behavior.

Contribution

It provides new insights into the microscopic dynamics and flow behavior during shear banding in Laponite suspensions, linking experimental observations to theoretical models.

Findings

Arrested gel-like dynamics in unsheared bands during shear localization

Observation of stick-slip oscillations in flow behavior

Dynamic light scattering effectively probes local flow and dynamics

Abstract

Shear localization in an aqueous clay suspension of Laponite is investigated through dynamic light scattering, which provides access both to the dynamics of the system (homodyne mode) and to the local velocity profile (heterodyne mode). When the shear bands form, a relaxation of the dynamics typical of a gel phase is observed in the unsheared band soon after flow stop, suggesting that an arrested dynamics is present during the shear localization regime. Periodic oscillations of the flow behavior, typical of a stick-slip phenomenon, are also observed when shear localization occurs. Both results are discussed in the light of various theoretical models for soft glassy materials.