Reversed extension flow

Jens Kromann Nielsen, Henrik K. Rasmussen

Research output: Contribution to journalJournal articleResearchpeer-review


Afilament stretching rheometer (FSR) was used for measuring the start-up of uni-axial elongational flow followed by reversed bi-axial flow, both with a constant elongational rate. A narrow molecular mass distribution linear polystyrene with a molecular weight of 145 kg / mole wis subjected to the start-up of elongation for three Hencky strain units and subsequently the reversed flow. The integral molecular stress function formulation within the 'interchain pressure' concept agrees with the experiments. In the experiments the Hencky strain at which the str~ss becomes zero (the recovery strain) in the reversed flow has been identified. The recovery strain is found to increase with elongational rate, and has a maximum value of approximately 1.45. The Doi Edwards model using any stretch evolution equation is not able to predict the correct level of the recovery strain.
Original languageEnglish
JournalJournal of Non-Newtonian Fluid Mechanics
Issue number1-2
Pages (from-to)15-19
Publication statusPublished - 2008


  • FSR
  • Reversed flow
  • Bi-axial
  • Uni-axial
  • Filement stretching rheometer


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