Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Brownian Motion and Transport

DY 25.11: Talk

Thursday, March 29, 2012, 12:30–12:45, MA 004

Microrheological Characterization of Acrylic Thickener Solutions — •Anne Kowalczyk and Norbert Willenbacher — Karlsruhe Institute of Technology (KIT), Institute of Mechanical Process Engineering and Mechanics, Gotthard-Franz-Str.3, 76128 Karlsruhe, Germany

The heterogeneous microstructure of three different acrylic thickeners with similar chemical composition but different molecular architecture has been characterized using 2D and 3D multi particle tracking (MPT). Thermal fluctuations of about 100 tracer particles are recorded at a time. We present a customized treatment of so-called tracing errors which occur in 2D tracking experiments which allows us to get physically meaningful results from statistical trajectory analysis for inhomogeneous fluids. We could show that tracer particles are homogeneously distributed and all show the same mobility for the thickener Viscalex HV30. For Sterocoll D the distribution of tracer particles is inhomogeneous, certain areas are not accessible, presumably due to a higher crosslink density, but all tracers exhibit similar mobility. Carbopol solutions show the highest degree of inhomogeneity, a substantial fraction of volume is inaccessible and in addition tracer mobility varies drastically in the remaining portion of the solutions, a fraction of particles is trapped in an elastic, gel-like environment, others can diffuse freely.