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

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, $G^{\prime }\sim t^{\beta }$, 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.

4 pages, 5 figures