An Eshelby model for the highly viscous flow

TL;DR

This paper develops an Eshelby-based model to describe the shear flow and dielectric alpha-process in molecular glass formers, linking local structural rearrangements to macroscopic relaxation spectra.

Contribution

It introduces a model using Eshelby's elasticity solution to connect local structural rearrangements with shear and dielectric relaxation behaviors in glasses.

Findings

Calculates recoverable compliance from local shear rearrangements.

Estimates the lifetime of symmetric double-well potentials.

Describes dielectric spectrum as a folding of relaxations with Debye process.

Abstract

The shear flow and the dielectric alpha-process in molecular glass formers is modeled in terms of local structural rearrangements which reverse a strong local shear. Using Eshelby's solution of the corresponding elasticity theory problem (J. D. Eshelby, Proc. Roy. Soc. A241, 376 (1957)), one can calculate the recoverable compliance and estimate the lifetime of the symmetric double-well potential characterizing such a structural rearrangement. A full modeling of the shear relaxation spectra requires an additional parametrization of the barrier density of these structural rearrangements. The dielectric relaxation spectrum can be described as a folding of these relaxations with the Debye process.