Berlin 2012 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: Focus: Rheology I (joint focus with DRG)
CPP 35.3: Talk
Thursday, March 29, 2012, 15:45–16:00, C 243
Rheological properties of living and dead microalgae suspensions at various concentrations: the crossover between shear thinning and apparent yield stress behavior — •Antoine Soulies1, Jack Legrand1, Jeremy Pruvost1, Cathy Castelain2, and Teodor Burghelea2 — 1Universite de Nantes, CNRS, GEPEA UMR-CNRS 6144, Bd de l'Universite, CRTT-BP 406, 44602 Saint- Nazaire Cedex, France — 2Universite de Nantes, CNRS, Laboratoire de Thermocinetique de Nantes, UMR 6607, La Chantrerie, Rue Christian Pauc, B.P. 50609, F-44306 Nantes Cedex 3, France
A systematic study of the rheological properties of solutions of microalgae suspensions (Chlorella) in a wide range of volume fractions is presented. At low volume fractions the suspensions display a Newtonian behavior and the volume fraction dependence of the viscosity can be well described by the Quemada model (Quemada 2006). For intermediate values of the volume fraction a shear thinning behavior is observed and the volume fraction dependence of the viscosity can be described by the Simha model (J. Appl. Phys, 23, 1952). For the largest volume fractions, an apparent yield stress behavior is observed. Increasing and decreasing stress ramps within this range of volume fractions indicate a thixotropic behavior. The rheological data acquired within the high concentration regime bears similarities with the measurements performed by Heymann et al. (Heymann et al. Phys. Rev E 75, 2007) on PMMA suspensions: irreversible flow behavior, dependence of the flow curve on the characteristic time of forcing. Solutions of dead microalgae generally behave similarly to that of living ones.