Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 11: POSTER Disperse Polymer Systems

CPP 11.42: Poster

Tuesday, March 28, 2006, 17:00–19:00, P3

Analytical centrifugation to describe rheological behaviours of concentrated suspensions — •Torsten Detloff, Titus Sobisch, and Dietmar Lerche — L.U.M. GmbH, Rudower Chaussee 29, 12489 Berlin, Germany

The flow behaviour of concentrated suspensions is mostly characterized by viscometric approaches. The interpretation of the results, especially at low shear rates, is often difficult due to sedimentation and particle migration within the viscometric gap. But studying separation processes can give information about the viscosity behaviour of such suspensions, because of the close connection between sedimentation kinetics and rheology. In this paper analytical centrifugation were used to determine the viscosity functions of spherical rigid particles in the nanometer range depending on volume concentrations between 5 and 47%. The measurement device - a multisample analytical centrifuge - LUMiSizer® (L.U.M. GmbH, Berlin Germany) employs the STEP™-Technology (Space and Time resolved Extinction Profiles), which allows to measure the intensity of transmitted light as function of time and position over the entire sample length simultaneously. From this data the values of the flux density function at different initial volume concentrations were determined and a viscosity law as functions of volume concentration obtained by fitting. The approach was applied to spherical biological cells and silica particles.