Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 1: DRG-DPG SYMPOSIUM Rheology I

CPP 1.5: Invited Talk

Monday, February 25, 2008, 11:00–11:30, C 130

Thermo-Rheological Properties of Fiber Networks — •Christian Friedrich, Yasmin Korth, and Martin Kühne — Freiburg Materials Reserch Center (FMF), University Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg i. Brsg., Germany

The dispersion of fibers (nm-thick and mikrom-long fibers) in matrices, without bundling or aggregation, is of crucial importance for the beneficial combination of fiber properties with those of matrix fluids. For multi-walled carbon nanotubes (mwCNT) dispersed in ionic liquids (IL), we developed a technique enabling good dispersion of these fibers in the matrix fluid. Using different analytical tools (rheology, centrifugation) we were able to discriminate gel-forming varieties of CNT from those who do not gel. For those who give gels, we identified the concentration regions in which networking is dominant. While the temperature dependence of fibers modulus is crucial for the understanding of gels modulus temperature dependence, the module scaling with concentration depends on the fibers persistence length. In the last part of our presentation we deal with possibilities of its determination on the basis of morphological as well as rheological techniques. Although mwCNT-dispersions are highly polydisperse in persistence, an estimation of gels plateau modulus with the MacKintosh-Model is possible.