Biaxial Deformations of Rubber: Entanglements or Elastic Fluctuations?

TL;DR

This paper evaluates the validity of the thermal elastic fluctuation mechanism in explaining large deformation behavior of rubber, comparing it with the slip-link model across different polymer networks.

Contribution

It tests the XGR theory against biaxial stress-strain data and compares its performance with the slip-link model, demonstrating comparable fitting quality.

Findings

Both XGR and slip-link models fit the data well.

XGR theory provides a satisfactory description across the entire deformation range.

The fitting qualities of the two theories are comparable.

Abstract

The classical theory of rubber elasticity fails in the regime of large deformation. The un- derlying physical mechanism has been under debate for long time. In this work, we test the recently proposed mechanism of thermal elastic fluctuations by Xing, Goldbart and Radzi- hovsky1 against the biaxial stress-strain data of three distinct polymer networks with very different network structures, synthesized by Urayama2 and Kawabata3 respectively. We find that both the two parameters version and the one-parameter version of the XGR theory provide satisfactory description of the elasticity in whole deformation range. For comparison, we also fit the same sets of data using the slip-link model by Edwards and Vilgis with four parameters. The fitting qualities of two theories are found to be comparable.