Thermal Fluctuations and Rubber Elasticity

TL;DR

This paper investigates how thermal elastic fluctuations influence rubber elasticity, revealing their role in modifying stress-strain behavior and explaining experimental observations like the Mooney-Rivlin peak.

Contribution

It introduces a new understanding of thermal fluctuation effects in rubber, linking microscopic fluctuations to macroscopic stress-strain relations and experimental features.

Findings

Thermal fluctuations qualitatively alter large-deformation stress-strain relations.

The mechanism explains the Mooney-Rivlin peak structure.

Predicted phonon correlation functions depend on external deformation.

Abstract

The effects of thermal elastic fluctuations in rubber materials are examined. It is shown that, due to an interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation, and shows a good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.