Fragmentation of liquid sheets of emulsion: competition between interfacial and viscous effects

Sprays of emulsion are used widely from cosmetics to agriculture. Understanding the governing principles of emulsion fragmentation allows for the design of sprays with desired characteristics, such as droplet size. Sprays are formed when liquid sheets and ligaments break up into droplets. The composition of a liquid sheet is known to affect its destabilization. Indeed, the addition of a dispersed phase, liquid or solid, reduces the expansion and lifetime of the liquid sheet. In this study, we investigate the destabilization of liquid sheets of emulsion. We vary the viscosity of the dispersed phase and alter surfactant concentrations to vary the spreading parameter. Using high-speed imaging, we capture the expansion and fragmentation of single-drop impacts of emulsions on a small surface. We show that both viscosity and interfacial properties influence the destabilization. We use a modified Capillary number to compare the effect of viscous and interfacial stresses on the fragmentation of liquid sheets of emulsion.