Elucidating on the drop impact dynamics of water-in-oil microemulsions via advanced rheometry
Mohammad Abboud, F. H. Yin, Maxim Piskunov, Ilia V. Roisman, Jeanette Hussong
Abstract
Microemulsions are promising for diverse applications, but their complex rheology, especially at high shear rates , poses characterization challenges. This study investigates the impact of water-in-oil microemulsion drops on flat and curved surfaces, focusing on the critical role of high-shear rheology. We assessed rheological properties across a wide range of shear rates by combining conventional methods, high-frequency rheometry, and a recently developed drop-impact viscometry (DIV) technique. DIV captures a substantial apparent viscosity increase (up to 12-fold) at high shear rates, enabling the prediction of maximum spreading and splashing thresholds. We observed complete splash suppression at high-impact velocities, where splashing is typically severe. These insights into high-shear rheological properties are crucial for optimizing microemulsion formulation and performance in applications such as spray and fuel injection.