Viscous Bursting of Suspended Films

Soap films break up by an inertial process. We present here the first observations on freely suspended films of long-chain polymers, where viscous effects are dominant and no surfactant is present. A hole is nucleated at time 0 and grows up to a radius $R(t)$ at time t. A surprising feature is that the liquid from the hole is not collected into a rim (as it is in soap films): The liquid spreads out without any significant change of the film thickness. The radius $R(t)$ grows exponentially with time, R∝exp(tτ) [while in soap films $R(t)$ is linear]. The rise time τ∝ηe2γ where η is viscosity, e is thickness (in the micron range), and γ is surface tension. A simple model is developed to explain this growth law.