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Rheologica Acta

, Volume 45, Issue 5, pp 755–764 | Cite as

Dependence of the zero shear-rate viscosity and the viscosity function of linear high-density polyethylenes on the mass-average molar mass and polydispersity

  • Florian J. Stadler
  • Christian Piel
  • Joachim Kaschta
  • Sascha Rulhoff
  • Walter Kaminsky
  • Helmut Münstedt
Original contribution

Abstract

Linear high-density polyethylenes with molar masses M w between 240 and 1,000,000 g/mol, obtained by metallocene catalysts, were characterized in shear using oscillatory and creep tests. The polydispersities of the molar mass distributions (MMDs) lay between 1 and 16. The resulting zero shear-rate viscosities η0 covered a range from 2.5×10−3 to around 108 Pas. Above a critical molar mass of M c≈2,900 g/mol, the experimental results can be described by the relation η0M w 3.6 , independently of the MMD. The oscillatory data were fitted with a Carreau–Yasuda equation. The resulting parameters were correlated to molecular structure. The parameter a, being a quantity for the width of the transition between the Newtonian and the non-Newtonian regime, showed a dependence on the molar mass M w but not on M w/M n. The parameter λ of the Carreau-Yasuda equation was found to be the reciprocal crossover frequency for all samples with a log-Gaussian MMD. λ depends on the molar mass M w and also on M w/M n.

Keywords

High-density polyethylene Zero shear-rate viscosity Mass-average molar mass Polydispersity Viscosity function Carreau–Yasuda model 

Notes

Acknowledgements

The authors would like to thank the Deutsche Forschungsgemeinschaft (German Research Foundation) for the financial support of this project. They would also like to thank Mrs. Inge Herzer of the University Erlangen-Nürnberg for the GPC-MALLS measurements. Additionally, discussions with Jens Stange and Dietmar Auhl of the University Erlangen-Nürnberg are gratefully acknowledged.

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Florian J. Stadler
    • 1
  • Christian Piel
    • 2
  • Joachim Kaschta
    • 1
  • Sascha Rulhoff
    • 2
  • Walter Kaminsky
    • 2
  • Helmut Münstedt
    • 1
  1. 1.Institute of Polymer MaterialsFriedrich-Alexander-University Erlangen-NürnbergErlangenGermany
  2. 2.Institute of Technical and Macromolecular ChemistryUniversity of HamburgHamburgGermany

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