Stress Relaxation of Entangled Polymer Networks

TL;DR

This study uses molecular dynamics simulations to analyze the non-linear stress-strain behavior of entangled polymer networks, highlighting the role of trapped entanglements and the applicability of the tube model in different conditions.

Contribution

It provides new simulation-based insights into stress-strain relations for dry and swollen networks, emphasizing the influence of entanglements and network models.

Findings

Tube model describes stress in both elongation and compression.

Total modulus decreases with swelling as (V_0/V)^{2/3}.

Phantom model applies only to short strand networks.

Abstract

The non-linear stress-strain relation for crosslinked polymer networks is studied using molecular dynamics simulations. Previously we demonstrated the importance of trapped entanglements in determining the elastic and relaxational properties of networks. Here we present new results for the stress versus strain for both dry and swollen networks. Models which limit the fluctuations of the network strands like the tube model are shown to describe the stress for both elongation and compression. For swollen networks, the total modulus is found to decrease like (V_0/V)^{2/3} and goes to the phantom model result only for short strand networks.