Shear banding in biphasic liquid-liquid systems.
In this Letter, we present the first systematic report of shear-induced banding in microconfined biphasic liquid-liquid systems, i.e., formation of alternating regions of high and low volume fraction of dispersed-phase droplets in a parallel plate flow cell. Such a flow-driven, gap-dependent phenomenon is only observed at low values of the viscosity ratio between the dispersed and the continuous phase, and in a given range of the applied shear rate. Based on rheological measurements, band formation is found to be associated with a viscosity decrease as compared to the homogeneous, structureless case, thus showing that system microstructure is somehow evolving towards reduced viscous dissipation under shear flow.
Dipartimento di Ingegneria chimica, Università di Napoli Federico II, Napoli 80125, Italy.
Sergio
S
Caserta
Marino
M
Simeone
Stefano
S
Guido