Dresden 2006 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 35: Ferro Fluids / Liquid Chrystals

DY 35.4: Vortrag

Mittwoch, 29. März 2006, 15:15–15:30, SCH 251

Rheology of a bidisperse inverse ferrofluid — •Robert Krauss, Reinhard Richter, and Ingo Rehberg — Experimentalphysik 5, Universität Bayreuth, D-95440 Bayreuth, Germany

By dispersing non-permeable particles in a common ferrofluid we obtain a so called inverse ferrofluid [1]. In our case fairly large polystyrene particles create magnetic holes which have magnetic moments opposite to the ferrofluid they are displacing. In previous studies we investigated the viscoelastic properties of a mono- vs a polydisperse inverse ferrofluid [2]. In order to quantify the influence of polydispersity we prepare samples of a bidisperse size distribution of spherical particles. The ratio of small to large particles is varied systematically. On the one hand rheological measurements are carried out to describe the viscoelastic properties of the magneto-rheological fluid. On the other hand we investigate optically the chain formation of the system in an external field by a long-range microscope. We compare the results with the ones obtained for monodisperse samples.

[1] A.T. Skjeltorp, Phys. Rev. Lett. 51, 2306 (1983).

[2] Ruben Saldivar-Guerrero, Reinhard Richter, Ingo Rehberg, Nuri Aksel, Lutz Heymann and Oliverio S. Rodriguez-Fernández, Viscoelasticity of mono- and polydisperse inverse ferrofluids, subm. to J. Chem. Phys. (2005).