Soft Condensed Matter Seminars
University of Montpeillier
Microscopic dynamics and failure precursors during the creep of a colloidal gel
We study the microscopic dynamics of a model fractal colloidal gel under load by coupling a small angle light scattering apparatus to a custom stress-controlled shear cell. We find that the creep consists of three regimes. After an instantaneous elastic jump, a power law (primary) creep, well described by linear viscoelasticity, is found to last several hours, during which the microscopic non affine dynamics is fully reversible. Upon deviation from the linear viscoelasticity, a sharp acceleration, localized in time, of the non affine dynamics is observed. These faster rearrangements precede the macroscopic failure of the gel by thousands of seconds: they thus are dynamic precursors of failure that allow one to predict the fate of the gel well before any rheological measurement.