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The effect of slip in the flow of a branched PP melt: experiments and simulations

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Abstract

In this paper visualisation and direct velocity profile measurement experiments for a branched polypropylene melt in a 10:1 axisymmetric contraction demonstrate the onset of wall slip. Video processing of the flow shows the formation of vortices and their diminution with increasing flow rate. Numerical simulations using a multimode K-BKZ viscoelastic and a purely viscous (Cross) model—both of them incorporating a nonlinear slip law—were used to predict the flow kinematics and dynamics as well as to deduce the slip velocity function by performing fitting to the velocity profiles. It was found that the numerical predictions agree well with the experimental results for the velocity profiles, and vortex formation, growth and reduction. It is suggested that such experiments (visualisation of entrance flow and direct velocity profile measurement) can be useful in evaluating the validity of constitutive equations and slip laws in the flow of polymer melts through processing equipment.

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Acknowledgements

Financial assistance from the Natural Sciences and Engineering Research Council (NSERC) of Canada and the General Secretariat for Research and Technology (GGET) of Greece are gratefully acknowledged. The authors are indebted to Prof. Alexander Gotsis of the University of Delft for providing rheological experimental data, especially on the elongational viscosity.

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Authors and Affiliations

  1. School of Mining Engineering and Metallurgy, National Technical University of Athens, Athens, Greece

    Evan Mitsoulis

  2. Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, Canada

    Igor B. Kazatchkov & Savvas G. Hatzikiriakos

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  1. Evan Mitsoulis
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  2. Igor B. Kazatchkov
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  3. Savvas G. Hatzikiriakos
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Correspondence to Savvas G. Hatzikiriakos.

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Mitsoulis, E., Kazatchkov, I.B. & Hatzikiriakos, S.G. The effect of slip in the flow of a branched PP melt: experiments and simulations. Rheol Acta 44, 418–426 (2005). https://doi.org/10.1007/s00397-004-0423-2

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  • DOI: https://doi.org/10.1007/s00397-004-0423-2

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