Time resolved viscoelastic properties during structural arrest and aging of a colloidal glass

TL;DR

This study investigates the evolution of viscoelastic properties during aging of a colloidal glass, revealing how structural relaxation time and yield stress change with age, and demonstrating a universal scaling of frequency dependence.

Contribution

It provides a systematic method to reconstruct frequency and strain dependence over time, unveiling the relationship between aging and viscoelastic properties in colloidal glasses.

Findings

Structural relaxation time increases exponentially with age.

Yield stress varies logarithmically with time.

Frequency dependence can be rescaled onto a master curve.

Abstract

Evolution of the energy landscape during physical aging of glassy materials can be understood from the frequency and strain dependence of the shear modulus but the non-stationary nature of these systems frustrates investigation of their instantaneous underlying properties. Using a series of time dependent measurements we systematically reconstruct the frequency and strain dependence as a function of age for a repulsive colloidal glass undergoing structural arrest. In this manner, we are able to unambiguously observe the structural relaxation time, which increases exponentially with sample age at short times. The yield stress varies logarithmically with time in the arrested state, consistent with recent simulation results, whereas the yield strain is nearly constant in this regime. Strikingly, the frequency dependence at fixed times can be rescaled onto a master curve, implying a simple connection between the aging of the system and the change in the frequency dependent modulus.