Rheologica Acta

, Volume 33, Issue 6, pp 506–516

Assessment of nonlinear strain measures for extensional and shearing flows of polymer melts

  • M. H. Wagner
  • J. Schaeffer

DOI: 10.1007/BF00366335

Cite this article as:
Wagner, M.H. & Schaeffer, J. Rheol Acta (1994) 33: 506. doi:10.1007/BF00366335


From stress-strain experiments in extensional and shearing flows, nonlinear strain measures and effective damping functions are derived for a polyisobutylene melt. The strain measures determined in planar extensional flow and in simple shear flow coincide. Experimental results are compared with predictions of two molecular theories, the Doi-Edwards model and the molecular stress function approach of Wagner and Schaeffer. Discrepancies between theories and experiment lead to a reconsideration of the classification of extensional flows. The symmetry of the flow field is identified and quantified as an important parameter influencing the strain measure, and a unifying strain measure for general extensional and shearing flows of polymer melts is presented.

Key words

Strain measuredamping functionextensional flowtransversely isotropic flowplanar flowshear flowDoi-Edwards modelmolecular stress functionclassification of extensional flowsplanarity index

Copyright information

© Steinkopff-Verlag 1994

Authors and Affiliations

  • M. H. Wagner
    • 1
  • J. Schaeffer
    • 1
  1. 1.Institut für KunststofftechnologieUniversität StuttgartStuttgartGermany
  2. 2.Institut für Kunststofftechnologie Universitat StuttgartStuttgartGermany