Constitutive modeling, non-linear behavior, and the stress-optic law

TL;DR

This paper reviews the constitutive modeling of rubbery polymers, focusing on non-linear behaviors, deviations from classical principles, and the applicability and breakdown of the stress-optic law under various conditions.

Contribution

It provides a comprehensive review of non-linear stress-strain behavior, deviations from superposition, and the conditions affecting the stress-optic law in rubbery polymers.

Findings

Deviations from Boltzmann superposition in non-linear regimes

Breakdown conditions of the stress-optic law identified

Empirical rules for nonlinear flow discussed

Abstract

Constitutive modelling of the stress-strain response of rubbery polymers is described, with an emphasis on the limits to linearity for both neat and filled rubber (the latter due to the Payne effect). Deviations from the Boltzmann superposition principle (time-strain invariance) under reversing strain histories are reviewed, including a discussion of the Mullins effect. The chapter also reviews the application of the stress optic law and the conditions causing its breakdown: internal stress, the glass transition, orientational coupling, and creep recovery. Different empirical rules for nonlinear flow are considered, including the Cox-Merz rule and the relations of Laun and Gleissle.