Nonlinear viscoelasticity of metastable complex fluids

TL;DR

This paper explains the nonlinear viscoelastic behavior of metastable complex fluids like colloidal glasses using mode coupling theory, providing insights that connect nonlinear measurements to linear properties.

Contribution

It offers a qualitative explanation for nonlinear viscoelasticity and validates it with mode coupling theory and experimental data on colloidal suspensions.

Findings

Storage modulus decreases monotonically with strain amplitude.

Loss modulus exhibits a peak before decreasing at larger strains.

Theoretical predictions agree reasonably with experimental measurements.

Abstract

Many metastable complex fluids such as colloidal glasses and gels show distinct nonlinear viscoelasticity with increasing oscillatory-strain amplitude; the storage modulus decreases monotonically as the strain amplitude increases whereas the loss modulus has a distinct peak before it decreases at larger strains. We present a qualitative argument to explain this ubiquitous behavior and use mode coupling theory (MCT) to confirm it. We compare theoretical predictions to the measured nonlinear viscoelasticity in a dense hard sphere colloidal suspensions; reasonable agreement is obtained. The argument given here can be used to obtain new information about linear viscoelasticity of metastable complex fluids from nonlinear strain measurements.