[SY-M1] Symposium M-1

[SY-M1] Structure-property Relations in Sheared Dense Flocculated Suspensions

Invited

^○Jan Vermant (ETH Zurich, Switzerland)

Rheological properties of dense attractive colloidal suspensions are characterized by time and deformation history dependent phenomena, which when reversible, are know as thixotropy. In the present work we will use a series of advanced characterization tools to elucidate the structure property relations in such systems. High frequency rheology is used to investigate the details of the colloidal interactions betweenthe particles and aggregates. Superposition rheology and 2D small amplitude oscilatory strain are used to investigate the mechanical properties, combined with stress jumps. Finally, high speed confocal rheoscopy is used to provide structural information on length scales of up to several 100 particles. The experiments show the role of microstructural anisotropy and and heterogeneity of the structure are caused by hydrodynamic stresses as particles and aggregates go on a "colloidal merry go round" during shear flow. The evolution of microstructural descriptors as a function of rate and strain is discussed. Comparison with recent simulation result on large scale structures will be included.
the goal is to give a hollistic view of the structure property relations in such systems.