Coupling between aging and convective motion in a colloidal glass of Laponite

TL;DR

This study investigates how aging affects thermal convection in a colloidal glass of Laponite, revealing a transition from turbulence to conduction as viscosity increases and highlighting the influence of concentration and pattern selection.

Contribution

It demonstrates the coupling between aging and convective motion in colloidal glasses, linking experimental observations to soft glassy rheology theories.

Findings

Convection duration decreases exponentially with colloidal concentration.

Higher viscosity leads to a transition from turbulent to conductive state.

Pattern selection influences the longevity of convection.

Abstract

We study thermal convection in a colloidal glass of Laponite in formation. Low concentration preparation are submitted to destabilizing vertical temperature gradient, and present a gradual transition from a turbulent convective state to a steady conductive state as their viscosity increases. The time spent under convection is found to depend strongly on sample concentration, decreasing exponentially with mass fraction of colloidal particles. Moreover, at fixed concentration, it also depends slightly on the pattern selected by the Rayleigh B\'{e}nard instability: more rolls maintain the convection state longer. This behavior can be interpreted with recent theoretical approaches of soft glassy material rheology.