Simulationsgestützte Schneckengeometrieoptimierung für die Herstellung von nanoverstärkten Polypropylencompounds

Translated title of the contribution: Simulation-based screw geometry optimization for the production of nano-reinforced polypropylene compounds

Joachim Winkler-Ebner

    Research output: ThesisMaster's Thesis

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    Nano-reinforced polymers are used to improve mechanical, thermal and rheological properties. They are often processed with co-rotating, intermeshing twin-screw extruders, at which the screw geometry configuration often represents the key parameter for the optimization and layout. The aim of this master thesis was to use the CFD-simulation software Polyflow from Ansys Inc. to simulate an existing screw geometry for the processing of two different PP nanocompounds in terms of shear rate, introduced shear energy, pressure and flow conditions. Furthermore, the simulated pressure values should be verified directly and the introduced shear energy should be verified indirectly at the injection molding compounder under practical conditions. In addition, the existing screw geometry should be optimized regarding intercalation and exfoliation of the layered silicate based on the simulation results. For the optimized screw geometry, the simulated pressure values as well as the introduced shear energy were also verified in practice. To examine the simulated values of the shear energy for their relevance at the injection molding compounder, for both screw geometries two factor levels of compounder screw speed and compounder back pressure were combined in a full factorial DoE. For all settings of this DoE, tensile specimens and SAXS plates were produced at the injection molding compounder. The results of the tensile tests were then statistically tested for correlations with the simulation results. It was found that the simulated pressure values, especially at low screw speeds as well as at elevated flow rates, corresponded excellently to the pressure values from practical experience. This confirms the plausibility of the simulation in general. The statistically evaluated tensile strengths also correlated very well with the simulated shear energies of both screw geometries and could be largely confirmed by the SAXS measurements. The simulated shear energies as well as the tensile strengths were significantly higher at elevated screw speeds. The lower shear energy values of the optimized screw geometry led to lower tensile strength values in almost all tensile tests. This disproves the hypothesis that a lower shear energy could be compensated by a higher value of the minimum residence time for the conditions investigated.
    Translated title of the contributionSimulation-based screw geometry optimization for the production of nano-reinforced polypropylene compounds
    Original languageGerman
    • Friesenbichler, Walter, Supervisor (internal)
    • Schuschnigg, Stephan, Co-Supervisor (internal)
    • Battisti, Markus, Co-Supervisor (internal)
    Award date19 Dec 2014
    Publication statusPublished - 2014

    Bibliographical note

    embargoed until null


    • extrusion
    • screw geometry optimization
    • screw simulation
    • Polyflow
    • injection-molding-compounding
    • layered silicate
    • nanocompound

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