Dynamics of a colloidal glass during stress-mediated structural arrest

TL;DR

This study investigates how stress influences the aging and structural arrest of colloidal glasses, revealing stress-dependent dynamics and supporting the concept of stress as an effective temperature in soft glassy materials.

Contribution

It provides experimental evidence for stress-induced structural arrest and validates the theoretical idea of stress as an effective temperature in soft glassy systems.

Findings

Loss modulus exceeds storage modulus at short times under intermediate stress

Arrest time depends exponentially on inverse stress

Stress narrows the loss peak, indicating structural arrest

Abstract

We employ parallel superposition rheology to study the dynamics of an aging colloidal glass in the presence of a mean field stress. Over a range of intermediate stresses, the loss modulus exceeds the storage modulus at short times but develops a maximum concomitant with a crossover between the two as the system ages. This is attended by a narrowing of the loss peak on increasing stress. We show that this feature is characteristic of the structural arrest in these materials, which is made observable on reasonable timescales by the activating influence of the stress. The arrest time displays an exponential dependence on inverse stress. These results provide experimental validation of the role of stress as an effective temperature in soft glassy systems as has been advanced in recent theoretical frameworks.