Rheology of glassy and jamming emulsions

We study the rheology of monodisperse and bidisperse emulsions with various droplet sizes (1 -- 2 diameter). Above a critical volume fraction , these systems exhibit solid-like behavior and possess a yield stress. Previous experiments suggest that for small thermal particles, rheology will see a glass transition at ; for large athermal systems, rheology will see a jamming transition at . However, simulations point out that at the crossover of thermal and athermal regimes, the glass and jamming transitions may both be observed in the same sample. Here we conduct an experiment by shearing four oil-in-water emulsions with a rheometer. We observe both a glass and a jamming transition for our smaller diameter droplets, and only a jamming transition for our larger diameter droplets. The bidisperse sample behaves similarly to the small droplet sample, with two transitions observed. Our rheological data fit well with both the Herschel-Bulkley model and the Three Component model. Our results suggest that liquid-solid transitions may depend on the type of particle.