Rheologica Acta

, Volume 50, Issue 1, pp 53–63 | Cite as

Influence of molecular parameters on the stress dependence of viscous and elastic properties of polypropylene melts in shear

  • Julia A. Resch
  • Joachim Kaschta
  • Friedrich Wolff
  • Helmut Münstedt
Original Contribution


The stress dependencies of the steady-state viscosity η and, particularly, that of the steady-state elastic compliance J e of various linear isotactic polypropylenes (PP) and one long-chain branched PP are investigated using creep-recovery tests. The creep stresses applied range from 2 to 10,000 Pa. In order to discuss the stress-dependent viscosity η and elastic compliance J e with respect to the influence of the weight average molar mass M w and the polydispersity factor M w/M n the PP are characterized by SEC–MALLS. For the linear PP, linear steady-state elastic compliances \(J_{\rm e}^0 \) in the range of 10 − 5–10 − 3 Pa − 1 are obtained depending on the molar mass distribution. \(J_{\rm e}^0 \) of the LCB-PP is distinctly higher and comes to lie at around 10 − 2 Pa − 1. \(J_{\rm e}^0 \) is found to be independent of M w but strongly dependent on polydispersity. η and J e decrease with increasing stress. For the linear PP, J e as a function of the stress τ is temperature independent. The higher M w/M n the stronger is the shear thinning of η and the more pronounced is the stress dependence of J e. For the LCB-PP, the strongest stress dependence of η and J e is observed. Furthermore, for all PP J e reacts more sensitively to an increasing stress than η. A qualitative explanation for the stronger stress dependence of J e compared to η is given by analyzing the contribution of long relaxation times to the viscosity and elasticity.


Polypropylene Viscosity Steady-state elastic compliance Stress dependence Molecular structure 



The authors would like to thank the German Research Foundation (DFG) for the financial support of this work. The contributions of Mrs. Inge Herzer, Mrs. Marika Sturm, and Mrs. Michelle Malter regarding the SEC–MALLS, the IR-spectroscopy, and the DSC measurements are gratefully acknowledged. Prof. Dr. Florian Stadler (School of Semiconductor and Chemical Engineering, Chonbuk National University) deserves acknowledgement for the calculation of the relaxation spectrum and its evaluation concerning η 0 and \(J_{\rm e}^0 \).


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Julia A. Resch
    • 1
  • Joachim Kaschta
    • 1
  • Friedrich Wolff
    • 1
  • Helmut Münstedt
    • 1
  1. 1.Institute of Polymer MaterialsFriedrich-Alexander-University Erlangen-NürnbergErlangenGermany

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