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

doi:10.1021/acsmacrolett.7b00900

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

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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. In this study, 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.

Authors:

^[1];

^[1]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: 2018-01-25

Research Org.:: Oak Ridge National Laboratory, Oak Ridge Leadership Computing Facility (OLCF); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1479793

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: ACS Macro Letters

Additional Journal Information:: Journal Volume: 7; Journal Issue: 2; Journal ID: ISSN 2161-1653

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE

Citation Formats


                    Xu, Wen -Sheng, Carrillo, Jan-Michael Y., Lam, Christopher N., Sumpter, Bobby G., and Wang, Yangyang. Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation.  United States: N. p., 2018. 
        Web.  doi:10.1021/acsmacrolett.7b00900.

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                    Xu, Wen -Sheng, Carrillo, Jan-Michael Y., Lam, Christopher N., Sumpter, Bobby G., & Wang, Yangyang. Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation.  United States.  doi:10.1021/acsmacrolett.7b00900.

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                    Xu, Wen -Sheng, Carrillo, Jan-Michael Y., Lam, Christopher N., Sumpter, Bobby G., and Wang, Yangyang. Thu .  
        "Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation".  United States.  doi:10.1021/acsmacrolett.7b00900.  https://www.osti.gov/servlets/purl/1479793.

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@article{osti_1479793,

  title        = {Molecular Dynamics Investigation of the Relaxation Mechanism of Entangled Polymers after a Large Step Deformation},

  author       = {Xu, Wen -Sheng and Carrillo, Jan-Michael Y. and Lam, Christopher N. and Sumpter, Bobby G. and Wang, Yangyang},

  abstractNote = {The chain retraction hypothesis of the tube model for nonlinear polymer rheology has been challenged by the recent small-angle neutron scattering (SANS) experiment. In this study, 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.},

  doi          = {10.1021/acsmacrolett.7b00900},

  journal      = {ACS Macro Letters},

  number       = 2,

  volume       = 7,

  place        = {United States},

  year         = {2018},

  month        = {1}

}

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DOI: 10.1021/acsmacrolett.7b00900

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