Transient overshoot extensional rheology of long-chain branched polyethylenes: Experimental and numerical comparisons between filament stretching and cross-slot flow

D.M. Hoyle, Qian Huang, D. Auhl, D. Hassell, Henrik K. Rasmussen, Anne Ladegaard Skov, O.G. Harlen, O. Hassager, T.C.B. McLeish

Research output: Contribution to journalJournal articleResearchpeer-review

572 Downloads (Pure)

Abstract

This work analyses the high-strain extensional behavior of long-chain branched polyethylenes, employing two novel extensional rheometer devices, the filament stretching rheometer and the cross-slot extensional rheometer. The filament stretching rheometer uses an active feedback loop to control the imposed strain rate on a filament, allowing Hencky strains of around 7 to be reached. The cross-slot extensional rheometer uses optical birefringence patterns to determine the steady-state extensional viscosity from planar stagnation point flow. The two methods probe different strain-rate regimes and in this paper we demonstrate the agreement when the operating regimes overlap and explore the steady-state extensional viscosity in the full strain-rate regime that these two complimentary techniques offer. For long-chain branched materials, the cross-slot birefringence images show a double cusp pattern around the outflow centre line (named W-cusps). Using constitutive modeling of the observed transient overshoot in extension seen in the filament stretching rheometer and using finite element simulations we show that the overshoot explains the W-cusps seen in the cross-slot extensional rheometer, further confirming the agreement between the two experimental techniques. © 2013 The Society of Rheology.
Original languageEnglish
JournalJournal of Rheology
Volume57
Issue number1
Pages (from-to)293-313
ISSN0148-6055
DOIs
Publication statusPublished - 2013

Bibliographical note

© 2013 The Society of Rheology

Keywords

  • Elasticity
  • Polyethylenes
  • Polymer melts
  • Rheology
  • Strain rate
  • Viscosity
  • Rheometers

Fingerprint

Dive into the research topics of 'Transient overshoot extensional rheology of long-chain branched polyethylenes: Experimental and numerical comparisons between filament stretching and cross-slot flow'. Together they form a unique fingerprint.

Cite this