The impact and deformation of a viscoelastic drop at the air-liquid interface.

The parameters that influence the deformation of viscoelastic drops impinging on a viscoelastic bath, and that lead to the detachment of these drops from the surface were investigated. A range of PEO solutions with different viscosities and molecular weights was used and the deformation of each drop during impact was observed using a high speed camera. The use of image analysis to measure the evolution of interfacial areas between the drop and the cavity formed during impact allowed the estimation of the potential and interfacial energies. This gave valuable information for the understanding of drop detachment. The drops need to retain a sufficiently high kinetic energy after impact in order to pass through the surface. It is therefore necessary to limit the deformation of the drop as well as the deformation of the bath (i.e. cavity depth) by increasing the drop viscosity. Reducing the kinetic energy of the drop at the moment of impact also limits deformation and promotes detachment of the drop.