Structure, Rheology, and Relaxation of Concentrated Emulsions
Jung-Ren Huang1*
1Physics, National Taiwan Normal University, Taipei, Taiwan
* presenting author:Jung-Ren Huang,
We employ a home-made Rheo-LS apparatus combining rheological (Rheo) and light scattering (LS) measurements to study shear-induced restructuring and rheology of concentrated monodisperse emulsions. The emulsions are subjected to large-amplitude oscillatory shear of variable amplitude and frequency. The LS data reflect droplet deformation as well as shear history-dependent inter-droplet structures. The rheological measurements display pseudoplasticity near zero shear rate and shear-thinning behavior at finite shear rates. The time-resolved and synchronous Rheo-LS measurements reveal detailed information about the complex structure-rheology relationship of emulsions. Shear disorders the droplets at low and high shear rates but induces order at medium shear rates. The apparent viscosity increases as the degree of inter-droplet order decreases. Indicated in the LS patterns, the relaxation of the emulsion subjected to a step strain exhibits two (fast and slow) characteristic times.

Keywords: rheology, light scattering, emulsion, shear-induced restructuring