Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation

Wen Sheng Xu, Jan Michael Y. Carrillo, Christopher N. Lam, Bobby G. Sumpter, Yangyang Wang

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

The chain retraction hypothesis of the tube model for nonlinear polymer rheology has been challenged by the recent small-angle neutron scattering (SANS) experiment (Wang, Z.; Lam, C. N.; Chen, W.-R.; Wang, W.; Liu, J.; Liu, Y.; Porcar, L.; Stanley, C. B.; Zhao, Z.; Hong, K.; Wang, Y., Fingerprinting Molecular Relaxation in Deformed Polymers. Phys. Rev. X 2017, 7, 031003). In this work, we further examine the microscopic relaxation mechanism of entangled polymer melts after a large step uniaxial extension by using large-scale molecular dynamics simulation. We show that the unique structural features associated with the chain retraction mechanism of the tube model are absent in our simulations, in agreement with the previous experimental results. In contrast to SANS experiments, molecular dynamics simulations allow us to accurately and unambiguously determine the evolution of the radius of gyration tensor of a long polymer chain after a large step deformation. Contrary to the prediction of the tube model, our simulations reveal that the radius of gyration in the perpendicular direction to stretching increases monotonically toward its equilibrium value throughout the stress relaxation. These results provide a critical step in improving our understanding of nonlinear rheology of entangled polymers.

Original languageEnglish
Pages (from-to)190-195
Number of pages6
JournalACS Macro Letters
Volume7
Issue number2
DOIs
StatePublished - Feb 20 2018

Funding

This research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy. The data analysis was performed at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facilities. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. We thank Yexin Zheng (U. Akron) for helpful discussions.

FundersFunder number
U.S. Department of Energy
Office of ScienceDE-AC05-00OR22725
Oak Ridge National Laboratory
UT-Battelle

    Fingerprint

    Dive into the research topics of 'Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation'. Together they form a unique fingerprint.

    Cite this