Dynamics of Internal Stresses and Scaling of Strain Recovery in an Aging Colloidal Gel

TL;DR

This study investigates how internal stresses relax and how strain recovery scales in an aging colloidal gel, revealing power-law decay and super-aging behavior with implications for understanding gel dynamics.

Contribution

It demonstrates the power-law decay of internal stresses and super-aging scaling in a colloidal gel, providing new insights into its relaxation and aging mechanisms.

Findings

Internal stresses decay as a weak power law over five decades of time.

The elastic modulus exhibits physical aging with a similar power-law behavior.

Strain recovery data collapse onto a master curve indicating super-aging dynamics.

Abstract

We monitor the relaxation of internal stresses in a fractal colloidal gel on cessation of flow and find a weak power law decay, $\sigma_i \sim t^{-\alpha}$ over 5 decades of time where $\alpha \approx 0.07$. The system exhibits physical aging of the elastic modulus, $G' \sim t^{\beta}$, with $\beta \approx \alpha$. Imposition of zero stress after waiting time $t_w$ results in strain recovery as the system relaxes without constraint. Remarkably, recoveries at different $t_w$ can be shifted to construct a master curve where data are scaled vertically by $1/\sigma_i(t_w)$ and plotted horizontally as $(t-t_w)/t_w^{\mu}$ where $\mu\approx 1.25$, indicative of a super-aging response.