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Version: acceptedVersion × Publisher: New York, NY [u.a.] : Pergamon Press × Subject: Carbon nanotubes ×

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    Correlation of carbon nanotube dispersability in aqueous surfactant solutions and polymers
    (New York, NY [u.a.] : Pergamon Press, 2009) Krause, Beate; Petzold, Gudrun; Pegel, Sven; Pötschke, Petra
    In order to assess the dispersability of carbon nanotube materials, tubes produced under different synthesis conditions were dispersed in aqueous surfactant solutions and the sedimentation behaviour under centrifugation forces was investigated using a LUMiFuge stability analyzer. The electrical percolation threshold of the nanotubes after melt mixing in polyamide 6.6 was determined and the state of dispersion was studied. As a general tendency, the nanotubes having better aqueous dispersion stability showed lower electrical percolation threshold and better nanotube dispersion in the composites. This indicates that the investigation of the stability of aqueous dispersions is also able to give information about the nanotubes inherent dispersability in polymer melts, both strongly influenced by the entanglement and agglomerate structure of the tubes within the as-produced nanotube materials. The shape of the nanotubes in the aqueous dispersions was assessed using a SYSMEX flow particle image analyzer and found to correspond to the shape observed from cryofractured surfaces of the polymer composites. © 2008 Elsevier Ltd. All rights reserved.
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    Dispersability and particle size distribution of CNTs in an aqueous surfactant dispersion as a function of ultrasonic treatment time
    (New York, NY [u.a.] : Pergamon Press, 2010) Krause, Beate; Mende, Mandy; Pötschke, Petra; Petzold, Gudrun
    The dispersability of carbon nanotubes (CNTs) was assessed by studying the sedimentation of CNTs dispersed in aqueous surfactant solutions at different ultrasonication treatment times using a LUMiSizer® apparatus under centrifugal forces. Different commercially available multiwalled CNTs, namely Baytubes® C150P, Nanocyl™ NC7000, Arkema Graphistrength® C100, and FutureCarbon CNT-MW showing quite different kinetics were compared. In addition, the particle size distributions were analyzed using dynamic light scattering and centrifugal separation analysis. The best dispersabilities were found for Nanocyl™ NC7000 and FutureCarbon CNT-MW; to prepare stable dispersions of Baytubes® C150P or Graphistrength® C100 five times the energy was needed. As a result of the centrifugal separation analysis, it was concluded that Nanocyl™ NC7000 and Baytubes® C150P were dispersed as single nanotubes using ultrasonic treatment whereas small agglomerates or bundles are existing in dispersions containing FutureCarbon CNT-MW and Graphistrength® C100. © 2010 Elsevier Ltd. All rights reserved.