Elongational viscosity of weakly entangled polymer melt via coarse-grained molecular dynamics simulation

TL;DR

This study uses an extended uniform extensional flow method in coarse-grained molecular dynamics to successfully measure the elongational viscosity of weakly entangled polymer melts from equilibrium to steady state, overcoming longstanding technical challenges.

Contribution

The paper extends the UEF method for Langevin dynamics, enabling accurate viscosity measurements of weakly entangled polymer melts in simulations.

Findings

Successfully observed elongational viscosity from equilibrium to steady state.

Extended UEF method overcomes previous technical limitations.

Demonstrated the method's effectiveness for weakly entangled polymers.

Abstract

We investigated the elongational flows of the weakly entangled linear polymer melt using a coarse-grained molecular dynamics simulation. We extended the uniform extensional flow (UEF) method developed by Nicholson and Rutledge (D. A. Nicholson and G. C. Rutledge, J. Chem. Phys., 145, 244903 (2016)) for application to Langevin dynamics. We succeeded in observing the elongational viscosity of the weakly entangled linear polymer melt from the equilibrium state to the steady state using the extended UEF method, whereas the conventional rectangular parallelepiped shape technique for extensional flows has failed to do so for over 20 years.