Rheological State Diagrams for Rough Colloids in Shear Flow

Shear-banding and microstructure of colloids in shear flow.

We shall discuss the following phenomena found in various colloidal systems in shear flow. We recently observed shear-banding in suspensions of fd-virus in a cylindrical shear cell. Small angle light scattering experiments revealed that the shear-banding transition is preceded by a relatively fast process (minutes) of nematic-to-paranematic phase separation during which inhomogeneities on the m...

Cluster Formation of Clay-like Colloids in Shear Flow

In Al2O3 suspensions, depending on the experimental conditions very different microstructures can be found, comprising fluid like suspensions, a repulsive structure, and a clustered microstructure. For technical processing in ceramics, the knowledge of the microstructure is of big importance, since it essentially determines the stability of a workpiece to be produced. To enlighten this topic, w...

Measuring advection and diffusion of colloids in shear flow.

An analysis of the dynamics of colloids in shear flow can be challenging because of the superposition of diffusion and advection. We present a method that separates the two motions, starting from the time-dependent particle coordinates. The restriction of the tracking to flow lanes and the subtraction of estimated advective displacements are combined in an iterative scheme that eventually makes...

Core--shell microgels as model colloids for rheological studies

We review recent work done on the rheology of thermosensitive suspensions. These systems consist of aqueous suspensions of coreshell particIes having asolid polystyrene core and a shell of thermosensitive crosslinked poly(N-isopropylacrylamide) (PNIPA). In cold water the thermosensitive PNIPA-network is swollen leading to a high effective volume fraction of the particles in suspension. Approach...

Signal Flow Graph Techniques for Sequential Circuit State Diagrams