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Title: Rouse mode analysis of chain relaxation in homopolymer melts

We use molecular dynamics simulations of the Kremer–Grest (KG) bead–spring model of polymer chains of length between 10 and 500, and a closely related analogue that allows for chain crossing, to clearly delineate the effects of entanglements on the length-scale-dependent chain relaxation in polymer melts. We analyze the resulting trajectories using the Rouse modes of the chains and find that entanglements strongly affect these modes. The relaxation rates of the chains show two limiting effective monomeric frictions, with the local modes experiencing much lower effective friction than the longer modes. The monomeric relaxation rates of longer modes vary approximately inversely with chain length due to kinetic confinement effects. The time-dependent relaxation of Rouse modes has a stretched exponential character with a minimum of stretching exponent in the vicinity of the entanglement chain length. None of these trends are found in models that allow for chain crossing. As a result, these facts, in combination, argue for the confined motion of chains for time scales between the entanglement time and their ultimate free diffusion.
Authors:
 [1] ;  [1] ;  [2] ;  [3]
  1. Columbia Univ., New York, NY (United States)
  2. Univ. of North Carolina, Chapel Hill, NC (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
OSTI Identifier:
1145768
Report Number(s):
SAND--2014-4138J
Journal ID: ISSN 0024-9297; 518305
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 47; Journal Issue: 19; Related Information: Proposed for publication in Macromolecules.; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE