Networks

TL;DR

This paper reviews the analysis methods of rubbery networks' large strain behavior, comparing phenomenological and molecular models, and discusses novel network architectures to improve elastomer properties.

Contribution

It provides a comprehensive comparison of continuum mechanics and molecular models, and explores innovative network architectures for enhanced elastomer performance.

Findings

Constraint models incorporate entanglements and steric effects.

Experimental validation of different models is discussed.

Novel architectures like double and interpenetrating networks improve properties.

Abstract

The two approaches to analyzing the large strain behavior of rubbery networks are phenomenologically, using strain energy functions drawn from continuum mechanics, and molecular models, which apply statistical mechanics to compute the effect of chain orientation on the entropy. The early rubber elasticity models ignored intermolecular interactions, whereas later developments ("constraint models") included the effect of entanglements or steric constraints on the mechanical stress. These constitutive equations for rubber elasticity are compared to experimental results, and the connection of network elasticity to the relaxation behaviour is discussed. For conventional elastomers there is a compromise between stiffness and strength. Different methods to circumvent this limitation are described. Examples are given of the properties obtained with novel network architectures, including interpenetrating networks, double networks, bimodal networks, miscible heterogeneous networks, and deswollen networks.