A Study on Material Optimization for Polypropylene Nanocomposites Based On Layered Silicates Using Elongational Flow Devices

Walter Friesenbichler, Markus Battisti, Andreas Neunhäuserer

    Publikation: KonferenzbeitragVortragForschungBegutachtung


    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 feature a higher
    Young’s Modulus and increased thermal conductivity.
    The aim of this study was to increase the material properties for polypropylene PNCs based on layered silicates by
    using elongational flow generating devices with super-imposed shear- and elongational flow and optimized nozzle
    geometries. The experiments were carried out at the injection molding compounder (IMC) at the Institute of
    Injection Molding at the Montanuniversität Leoben. Two different materials were tested. The first material used was
    a lower viscous homopolymer and the second material a higher viscous block copolymer. The formulation of the
    compounds was constant at 90 wt% polypropylene, 5 % organoclay and 5 %compatibilizer. Earlier works [1]
    showed that there is a significant correlation between die geometries and mechanical properties of PNCs. In order to
    gain a better understanding about the differences in influence for various nozzle geometries, five different
    hyperbolical and conical nozzles were designed. The varying factors were the nozzle length, the exit diameter and
    the injection speed which correlates with the elongation rate and shear rate. The influence of these parameters was
    tested for two different materials with a full factorial 23 design (DoE) including two center-points. Additionally the
    influence of the investigated factors on intercalation and exfoliation with SAXS-measurements was studied.
    The results of the tensile tests showed, that there is more room for influencing the Young’s Modulus of the lower
    viscous homopolymer (FIGURE 1), therefore better results for this material were achieved. 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. In FIGURE 1
    hLr describes a long hyperbolical nozzle with small exit diameter, and hlR describes a short hyperbolical with a big
    exit diameter. The same notation was applied for conical dies which can be identified by the prefix k.
    As displayed in FIGURE 1, the best results were
    achieved with the short hyperbolical die
    accompanied with a big exit diameter at the slow
    injection flow rate. This indicates that with this
    setting, the optimal level and balance between
    intercalation and exfoliation was reached. In near
    future, further intensive research, especially
    concerning a 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.
    PublikationsstatusVeröffentlicht - 11 Juni 2015
    VeranstaltungPPS-31 31st International Conference of the POLYMER PROCESSING SOCIETY - JUNGMUN Sightseeing Complex, SEOGWIPO City, Jeju, Südkorea
    Dauer: 7 Juni 201511 Juni 2015


    KonferenzPPS-31 31st International Conference of the POLYMER PROCESSING SOCIETY

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