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Title: Flow induced migration in polymer melts – Theory and simulation

Flow induced migration, whereby polymer melts are fractionated by molecular weight across a flow field, represents a significant complication in the processing of polymer melts. Despite its long history, such phenomena remain relatively poorly understood. Here a simple analytical theory is presented which predicts the phenomena based on well-established principles of non-equilibrium thermodynamics. It is unambiguously shown that for purely viscous materials, a gradient in shear rate is needed to drive migration; for purely viscometric flows no migration is expected. Molecular scale simulations of flow migration effects in dense polymer melts are also presented. In shear flow the melts exhibit similar behavior as the quiescent case; a constant shear rate across the gap does not induce chain length based migration. In comparison, parabolic flow causes profound migration for both unentangled and entangled melts. These findings are consistent with the analytical theory. The picture that emerges is consistent with flow induced migration mechanisms predominating over competing chain degradation mechanisms.
Authors:
;  [1]
  1. Department of Chemical and Biological Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401 (United States)
Publication Date:
OSTI Identifier:
22391780
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1662; Journal Issue: 1; Conference: International Conference on Novel Trends in Rheology VI, Zlin (Czech Republic), 28-29 Jul 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; EQUILIBRIUM; MOLECULAR WEIGHT; POLYMERS; SHEAR; THERMODYNAMICS; VISCOSITY; VISCOUS FLOW