Coupling between aging and convective motion in a colloidal glass of Laponite
LEAF-NL, Departamento de Ingeniera Mecanica, Universidad de Chile, Beaucheff 850, Santiago, Chile
Corresponding author: a Ludovic.Bellon@ens-lyon.fr
Revised: 26 January 2007
Published online: 15 February 2007
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 Bénard instability: more rolls maintain the convection state longer. This behavior can be interpreted with recent theoretical approaches of soft glassy material rheology.
PACS: 24.25.+f – Natural convection / 61.43.Fs – Glasses / 61.20.Lc – Time-dependent properties; relaxation
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007