Relation between extensional viscosity and polymer conformation in dilute polymer solutions

TL;DR

This study uses dissipative particle dynamics simulations to explore how polymer conformation influences extensional viscosity in dilute solutions, revealing strain hardening and a quantitative relation based on gyration radii.

Contribution

It introduces a novel analysis method linking extensional viscosity growth to polymer gyration radii, providing a unified description across different chain lengths and concentrations.

Findings

Polymer stretching increases with high extension rates.

Extensional viscosity exhibits strain hardening behavior.

The model relates viscosity growth to gyration radii and their derivatives.

Abstract

We investigate extensional viscosity and polymer conformation in dilute polymer solutions under uniaxial extensional flow using dissipative particle dynamics simulations. At high extension rates, polymers are significantly stretched by extensional flows, and the extensional viscosity growth function exhibits strain hardening. To reveal their quantitative relation, we adopt an analysis method based on the Rouse-type model. We demonstrate that the extensional viscosity growth function is determined by the instantaneous gyration radii in the parallel and perpendicular directions to the extensional direction and their time derivatives. Our approach also provides a unified description of the steady-state extensional viscosity of dilute polymer solutions for various chain lengths and concentrations in terms of the polymer gyration radius.