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~R apparatus under centrifugal forces. Different commercially available multiwalled CNTs, namely Baytubes~R C150P, Nanocyl~(TM) NC7000, Arkema Graphi-strength~R 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~(TM) NC7000 and FutureCarbon CNT-MW; to prepare stable dispersions of Baytubes~R C150P or Graphistrength~R C100 five times the energy was needed. As a result of the centrifugal separation analysis, it was concluded that Nanocyl~(TM) NC7000 and Baytubes~R C150P were dispersed as single nanotubes using ultrasonic treatment whereas small agglomerates or bundles are existing in dispersions containing FutureCarbon CNT-MW and Graphistrength~R C100.
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