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Title: Numerical simulation of viscoelastic layer rearrangement in polymer melts using OpenFOAM®

In addition to their shear-thinning behavior, polymer melts are characterized by first and second normal stress differences, which cause secondary motions. Polymer coextrusion processes involve viscoelastic two-phase flows that influence layer formation. Using polymer melts with different pigmentation makes visible the layers deformed by second normal stress differences. We used a new solver for the OpenFOAM CFD toolbox which handles viscoelastic two-phase flows. A derivative of the volume-of-fluid (VoF) methodology was employed to describe the interface. Different types of polymer melt, such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were investigated. In a coextrusion process, the less viscous phase usually tends to encapsulate the more viscous one. However, the different viscoelastic properties of the melts also influence interface deformation. The materials were characterized by small-amplitude oscillatory-shear rheometry, and a multimode Giesekus model was used to fit shear viscosity, storage and loss modulus. Our simulations also took interfacial tension into account. Experimental observations and corresponding numerical simulations were found to be in good accordance.
Authors:
;  [1]
  1. Institute of Polymer Extrusion and Compounding, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz (Austria)
Publication Date:
OSTI Identifier:
22391851
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1664; Journal Issue: 1; Conference: PPS-30: 30. International Conference of the Polymer Processing Society, Cleveland, OH (United States), 6-12 Jun 2014; 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; COEXTRUSION; COMPOSITE MATERIALS; COMPUTERIZED SIMULATION; DEFORMATION; FLUIDS; INTERFACES; LAYERS; POLYESTERS; POLYETHYLENES; POLYPROPYLENE; SHEAR; STRESSES; SURFACE TENSION; SYNTHETIC MATERIALS; TWO-PHASE FLOW; VISCOSITY