Axial thinning of a liquid bridge of polymer solution between spherical surfaces

Capillary bridges between particles are encountered in a wide range of situations in nature and the industry. The force exerted by water between grains allows us, for instance, to build sandcastles. The characterization of liquid bridges between spherical surfaces is important in describing the transport and mixing of wet granular materials. When the two particles are separated, the extensional thinning of a Newtonian liquid results in an abrupt breakup of the bridge. However, the presence of a small amount of polymers dispersed in the liquid delays this break-up. The thinning and break-up of liquid bridges of polymer solutions have been investigated on planar surfaces. In this study, we explore the role of substrate geometry on the evolution of the capillary bridge between two particles. We investigate the thinning of a liquid bridge of dilute and semi-dilute polymer solution between two spherical surfaces. We use high-speed imaging to study the evolution of the shape and the minimum diameter of the bridge. We vary the concentration and molecular weight of the polymer solutions used to characterize the influence of the surface shape on the thinning of a liquid bridge.