(268i) The Role of End-Plate Wetting in the Filament Formation and Break-up of High Surface Tension, Strain Hardening Fluids

We investigated the effects of end-plate wetting on the filament formation and thinning leading to break-up of a high surface tension, strain hardening polymer solution – a 30% hydrolyzed poly(acrylamide-co-acrylate) in water. For the low aspect ratios and small volumes of fluid that we investigated, we found a dramatic effect of different end-plate combinations ranging from strongly wetting to strongly non-wetting on various aspects of filament formation and break-up. For some end-plate combinations, the final volume transfer to the top plate is strongly affected by both fluid volume and the imposed rate of plate displacement which we rationalize based on the work of adhesion. For cases where the top end-plate is non-wetting, we observed highly shortened filament thinning profiles accompanied by significantly lower apparent relaxation times. We fit the time evolution of the filament diameter with an empirical expression with a time-dependent effective relaxation time, much different from the classic single exponential expression from Entov and Hinch. We will discuss the implications of our findings in the context of roll-to-roll processes on viscoelastic solutions involving rollers with different materials.