Flow curves of dense colloidal dispersions: schematic model analysis of the shear-dependent viscosity near the colloidal glass transition

摘要

A recently proposed schematic model for the non--linear rheology of densecolloidal dispersions is compared to flow curves measured in suspensions thatconsist of thermosensitive particles. The volume fraction of this purelyrepulsive model system can be adjusted by changing temperature. Hence, highvolume fractions ($\phi \leq 0.63$) can be achieved in a reproducible manner.The quantitative analysis of the flow curves suggests that the theoreticalapproach captures the increase of the low shear viscosity with increasingdensity, the shear thinning for increasing shear rate, and the yielding of asoft glassy solid. Variations of the high shear viscosity can be traced back tohydrodynamic interactions which are not contained in the present approach butcan be incorporated into the data analysis by an appropriate rescaling.