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Author: Kretzschmar, Bernd × Author: Müller, Michael Thomas × Author: Pötschke, Petra × End date: 2023 × Start date: 2020 × Has files: Yes ×

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    Influence of a supplemental filler in twin-screw extruded PP/CNT composites using masterbatch dilution
    (Melville, NY : AIP, 2019) Müller, Michael Thomas; Krause, Beate; Kretzschmar, Bernd; Pötschke, Petra
    In this study commercially available multiwalled carbon nanotubes (2-8 wt.%) were incorporated in polypropylene (PP) by direct powder feeding or by a masterbatch dilution procedure using a twin-screw extruder. The influence of a supplemental, electrical non-conductive talc or electrically conductive carbon black (CB), filler on the resulting composite properties was investigated. In comparison to the direct carbon nanotube (CNT) incorporation the masterbatch dilution step resulted in improved CNT macro dispersion. The use of the supplemental fillers CB or talc does not show a significant influence on the CNT dispersion state. When compared to direct CNT incorporation, the second compounding process involved in masterbatch dilution leads to higher electrical resistivity of injection molded samples. On the other hand, the supplemental fillers talc or CB decreased the electrical resistivity values. With the addition of talc or CB an increase of the Young’s modulus due to the reinforcing effect of the second filler was achieved. However, no synergistic effect between the used supplemental fillers and the CNT on the mechanical properties was obtained.
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    Influence of feeding conditions in twin-screw extrusion of PP/MWCNT composites on electrical and mechanical properties
    (Barking : Elsevier, 2011) Müller, Michael Thomas; Krause, Beate; Kretzschmar, Bernd; Pötschke, Petra
    The influence of feeding conditions of multiwalled carbon nanotube (MWCNT) materials, namely Baytubes® C150P and Nanocyl™ NC7000, into polypropylene (PP) was investigated with respect to achieving suitable nanotube dispersion, high electrical conductivity, and good mechanical properties. Both MWCNT materials were fed at selected concentrations either in the hopper of the twin-screw extruder or using a side feeder under otherwise identical extrusion conditions (rotation speed, throughput, temperature profile) using a Berstorff ZE 25 twin-screw extruder. Afterwards, injection molding was performed under identical conditions. The results indicate that the more compact Baytubes® C150P agglomerates should be added into the hopper, as the dispersion assessed by light microscopy is better, electrical resistivities measured on compression and injection molded samples are lower, and elastic modulus, yield strength and impact strength are higher as compared to side feeding. On the other hand, for the more loosely packed Nanocyl™ NC7000 agglomerates, addition using the side feeder leads to better dispersion, lower electrical resistivity, and higher mechanical properties. © 2011 Elsevier Ltd.