Filters

20123

More filters

20233
Reset filters

Settings

search.filters.applied.f.access: openAccess × End date: 2012 × Start date: 2012 × Version: acceptedVersion ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A successful approach to disperse MWCNTs in polyethylene by melt mixing using polyethylene glycol as additive
    (Oxford : Elsevier Science, 2012) Müller, Michael Thomas; Krause, Beate; Pötschke, Petra
    An additive-assisted one-step melt mixing approach was developed to produce nanocomposites based on linear low density polyethylene (LLDPE) with multiwalled carbon nanotube (MWCNT). The polymer granules, nanotube powder (2 wt% Nanocyl™ NC7000) and 1-10 wt% of the non-ionic additives poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO) with molar masses between 100 g/mol and 100,000 g/mol were simply fed together in the hopper of a small-scale DSM Xplore 15 twin-screw microcompounder. The produced MWCNT/LLDPE composites showed excellent MWCNT dispersion and highly improved electrical properties as compared to samples without the additive, whereas the effects depend on the amount and molar mass of the additive. When 7 wt% PEG (2000 g/mol) were used, a reduction of the electrical percolation threshold from 2.5 wt% to 1.5 wt% was achieved. © 2012 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Influence of different carbon nanotubes on the electrical and mechanical properties of melt mixed poly(ether sulfone)-multi walled carbon nanotube composites
    (Barking : Elsevier, 2012) Chakraborty, Sourav; Pionteck, Jürgen; Krause, Beate; Banerjee, Susanta; Voit, Brigitte
    Commercial Udel® poly(ether sulfone) (PSU) was filled with three different commercially available multiwalled carbon nanotubes (MWCNTs) by small scale melt mixing. The MWCNTs were as grown NC 7000 and two of its derivatives prepared by ball milling treatment. One of them was unmodified (NC 3150); the other was amino modified (NC 3152). The main difference beside the reactivity was the reduced aspect ratio of NC 3150 and NC 3152 caused by ball milling process. All PSU/MWCNT composites with similar filler content were prepared under fixed processing conditions and comparative analysis of their electrical and mechanical properties were performed and were correlated with their microstructure, characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A non-uniform MWCNT dispersion was observed in all composites. The MWCNTs were present in form of agglomerates in the size of 10-60. μm whereas the deagglomerated part was homogeneously distributed in the PSU matrix. The differences in the agglomeration states correlate with the variations of properties between different PSU/MWCNT composites. The lowest electrical percolation threshold of 0.25-0.5. wt.% was observed for the shortened non-functionalized MWCNT composites and the highest for amine-modified MWCNT composites (ca. 1.5. wt.%). The tensile behavior of the three composites was only slightly altered with CNT loading as compared to the pure PSU. However, the elongation at break showed a reduction with MWCNT loading and the reduction was least for composite with best MWCNT dispersion. © 2012 Elsevier Ltd.