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Author: Boldt, Regine × Author: Pötschke, Petra × Author: Socher, Robert × End date: 2023 × Start date: 2020 ×

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    The influence of matrix viscosity on MWCNT dispersion and electrical properties in different thermoplastic nanocomposites
    (Oxford : Elsevier Science, 2012) Socher, Robert; Krause, Beate; Müller, Michael T.; Boldt, Regine; Pötschke, Petra
    Composites of MWCNTs having each three different levels of matrix viscosity with five different polymers (polyamide 12, polybutylene terephthalate, polycarbonate, polyetheretherketone and low density polyethylene) were melt mixed to identify the general influence of matrix viscosity on the electrical properties and the state of MWCNT dispersion. Huge differences in the electrical percolation thresholds were found using the same polymer matrix with different viscosity grades. The lowest percolation thresholds were always found in the composites based on the low viscosity matrix. The state of primary MWCNT agglomerate dispersion increased with increasing matrix viscosity due to the higher input of mixing energy. TEM investigations showed nanoagglomerated structures in the low viscosity samples which are obviously needed to achieve low resistivity values. The effect of nanotube shortening was quantified using two different viscosity grades of polycarbonate. Due to the higher mixing energy input the nanotube shortening was more pronounced in the high viscosity matrix which partially explains the higher percolation threshold. © 2011 Elsevier Ltd. All rights reserved.
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    Melt mixed nano composites of PA12 with MWNTs: Influence of MWNT and matrix properties on macrodispersion and electrical properties
    (Barking : Elsevier, 2011) Socher, Robert; Krause, Beate; Boldt, Regine; Hermasch, Sylvia; Wursche, Roland; Pötschke, Petra
    Nanocomposites containing four different polyamide 12 (PA12) types and three grades of multiwalled carbon nanotubes (MWNTs) were prepared via small-scale melt processing to study the effect of different MWNTs and the influence of polymer properties on the dispersion of the fillers and the electrical properties of the composites. Under the selected mixing conditions the lowest electrical percolation threshold of 0.7. wt.% was found for Nanocyl™ NC7000 in low viscous PA12. Moreover, big influences of the end group functionality (acid or amine excess) and the melt viscosity of the matrix were found. Composites of PA12 with acid excess showed lower percolation thresholds than those based on amine terminated materials. At constant end group ratio low viscous matrices resulted in lower percolation thresholds than high viscous materials. The best MWNT dispersion was obtained in both high viscous PA12 composites. In these systems the mixing speed was varied indicating an optimum concerning electrical conductivity at 150 rpm as compared to 50 and 250 rpm. © 2010 Elsevier Ltd.