Aging after shear rejuvenation in a soft glassy colloidal suspension: evidence for two different regimes

TL;DR

This study investigates aging behaviors in a soft glassy colloidal suspension after shear rejuvenation, revealing two distinct regimes depending on whether the sample is rejuvenated before or after gelation, with different aging dynamics observed.

Contribution

It provides new insights into the aging regimes of colloidal suspensions post-shear, introducing an original protocol for measuring correlation functions in fast-aging gelled samples.

Findings

Two aging regimes identified based on gelation state

Shear fully rejuvenates samples before gelation

Fast aging with power-law relaxation observed in gelled samples

Abstract

The aging dynamics after shear rejuvenation in a glassy, charged clay suspension have been investigated through dynamic light scattering (DLS). Two different aging regimes are observed: one is attained if the sample is rejuvenated before its gelation and one after the rejuvenation of the gelled sample. In the first regime, the application of shear fully rejuvenates the sample, as the system dynamics soon after shear cessation follow the same aging evolution characteristic of normal aging. In the second regime, aging proceeds very fast after shear rejuvenation, and classical DLS cannot be used. An original protocol to measure an ensemble averaged intensity correlation function is proposed and its consistency with classical DLS is verified. The fast aging dynamics of rejuvenated gelled samples exhibit a power law dependence of the slow relaxation time on the waiting time.