A Hybrid Model of Rubber Elasticity in Simple Extension

TL;DR

This paper introduces a hybrid thermodynamic model for rubber elasticity that integrates entropic and energetic contributions, capturing the transition from entropy-driven to energy-driven elasticity in polymers, including crystallizing types.

Contribution

It presents a novel continuous transition model from entropy to energetic elasticity and a simple stress-induced crystallization model for crystallizing polymers.

Findings

Model demonstrates a smooth transition from entropy to energetic elasticity.

Captures stress reinforcement due to polymer crystallization.

Applicable to amorphous and crystallizing polymers.

Abstract

A thermodynamically related model is developed for describing elastic rubber-like behavior of amorphous and crystallizing polymers and demonstrated on example of simple extension. Both the “entropic” and “energetic” motions of polymer chains that contribute in macroscopic elastic deformation are taken into account. The model displays a continuous transition from entropy to energetic elasticity, without common singularity caused by finite extensibility of polymer chains. A multi-scale molecular approach, based on recent literature concepts has been employed for evaluations of continuum parameters. For crystallizing polymers, a simple model is developed for the stress-induced crystallization, which describes the stress reinforcement caused by the formation of long, needle-like polymer crystals.