Materialoptimierung von schichtsilikatverstärkten Polypropylen-Nanocompounds mittels Einsatz von dehnströmungserzeugenden Düsen

Translated title of the contribution: A study on material optimization for polypropylene-nanocomposites based on layered silicates by using elongational flow generating devices

Andreas Neunhäuserer

    Research output: ThesisMaster's Thesis

    Abstract

    Over the last years, the use of nano-reinforced polymers increased due to their superior mechanical, thermal and rheological properties. Polymer nanocomposites (PNCs) which are based on layered silicates are accompanied by a higher Young’s-Modulus. The decisive parameters therefore are the level of intercalation and exfoliation. The aim of this master thesis was to increase the material properties for polypropylene nanocomposites based on layered silicates by using elongational flow generating devices with super-imposed shear- and elongational flow and optimized nozzle geometries. In order to gain knowledge about the differences in influence for various nozzle geometries, five different hyperbolical and conical nozzles were designed. The varying factors are the nozzle length, the exit radius and the injection speed which correlates with the elongation rate and shear rate. The influence of these parameters was tested with a full factorial 2^3 design (DoE). This approach should provide information concerning the influence of the absolute elongation, the elongational speed and the shear rate on the Young’s-Modulus of PNCs. The factorial design was tested for two different materials, the first material was a lower viscous homopolymer and the second material a higher viscous block copolymer. The influence of the investigated factors on the intercalation and exfoliation was checked with SAXS-measurements. In the next step, based on the results of the tensile tests, a flexible multi nozzle system was developed. This multi nozzle system is applicable for the injection molding machine and for the extrusion line. The results of the tensile tests showed, that there is more room for influencing the Young’s Modulus of the lower viscous homopolymer, therefore better results for this material were achieved. The analysis of the DoE showed, that the best results were achieved with a hyperbolical nozzle (low level of elongation, low rate of elongation). On the opposite, it was not possible to achieve satisfying results for the higher viscous block copolymer. This is possibly caused by an inappropriate process window or the difference in viscosity of compatibilizer and block copolymer. The results of the temperature and pressure measurements were as expected for the hyperbolical nozzles. Long nozzles with high elongation needed more pressure accompanied with a higher temperature raise. The results of the conical nozzles were partly unexpected. These could result out of the dead zones that develop within sharp conical nozzles. In near future, further intensive research, especially concerning the flexible multi nozzle system, is planned. Furthermore, the processing temperatures for the block copolymer will be lowered and the PP will be additivated with a stabilizer against thermo-oxidative degradation.
    Translated title of the contributionA study on material optimization for polypropylene-nanocomposites based on layered silicates by using elongational flow generating devices
    Original languageGerman
    QualificationDipl.-Ing.
    Supervisors/Advisors
    • Battisti, Markus, Co-Supervisor (internal)
    • Friesenbichler, Walter, Supervisor (internal)
    Award date24 Oct 2014
    Publication statusPublished - 2014

    Bibliographical note

    embargoed until 18-09-2017

    Keywords

    • elongational viscosity
    • nanocomposites
    • layered silicates
    • nano-reinforced polymers
    • injection molding
    • compounding

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