Particle-stabilized emulsions comprised of solid droplets.
We kinetically stabilize oil-in-water emulsions comprising paraffin crystals by adsorbing solid particles (silica) of colloidal size at the oil/water interface. We obtain a set of emulsions that are quiescently stable for a long period of time (months), while the same emulsions are destabilized after only a few hours in the presence of surfactant molecules alone. The emulsions are submitted to a shear stress in order to probe their stability under flow conditions. Partial coalescence and gelation occur when the shear is applied for a sufficiently long period of time. The experiments reveal the existence of a critical droplet mass fraction, phi*, that defines a sharp transition between slow and fast gelation. The process of gelation is rather slow for phi < phi*, occurring at the scale of hours, and becomes almost instantaneous above phi*.
Giermanska-Kahn
J
J
Centre de Recherche Paul Pascal, CNRS, VA. Schweitzer, 33600 Pessac, France.
Laine
V
V
Arditty
S
S
Schmitt
V
V
Leal-Calderon
F
F