Characterization of carbon black dispersions by multisample analytical centrifugation
T. Sobisch, D. Lerche, N. Quintas, T. Detloff¹; PARTEC 2007.
Abstract: Carbon black dispersions are widely applied in inks and paints. A high dispersity and high degree of dispersion stability is of paramount importance. Analytical centrifugation with photometric detection revealed a surprising phenomenon in several industrial application labs, the so called "Backfolding". After a distinct time of centrifugation a marked reduction in turbidity is observed in the supernatant separated so far. A close correlation was supsected betweent he degree of the "backfolding" and product performance. A detailed investigation of this phenomenon was performed in the centrifugal field as a function of preparation conditions of carbon black dispersions, volume fraction, centrifugal accelearation, temperature, viscosity and additives. Analytical centrifugation can be used for an integral characterization of dispersion quality influenced by viscosity, density difference, particle stabilization and particle size distribution. The new multisample approach uses the STEP-technology. Space and time resolved extinction profiles quantify the alteration of particle concentration and packing behavior during centrifugation without the need for sample dilution. The latter is a necessary prerequisite for ensuring that the liquid dispersions maintain their original properties.
Key words: Carbon black • Colloid stability • Ink dispersions • Sedimentation • Particle size distribution • Aggregation • Turbidity • LUMiSizer
¹ L.U.M. GmbH, Rudower Chaussee 29 (OWZ), 12489 Berlin, Germany.Contact us
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