Rupture of soapy objects
Par Emmanuelle RIO, Laboratoire de Physique des Solides, Université Paris Sud
Mardi 30 Avril, 14h00, Salle des séminaires (215), 2ème étage, Bâtiment A4N
Abstract :
Bubbles, soap films or foams are ephemeral objects whose lifetime can vary a lot depending on the soapy solution used to make them or on the atmospheric humidity, for example. In this seminar, I will explore the influence of these parameter on the film rupture.
First, I will be present the breaking of a soap film during its generation (Figure 1). I will show that their lifetime provides a prediction for the difference in surface tension between the bottom and the top of the film, which is of the order of 1 – 2 mN/m. Then, I will explore the impact of the physicochemicals and of the humidity of the air.
Second, I will focus on surface bubbles (Figure 2), whose rupture localisation depends on the surfactant concentration of the solution. Indeed, at high concentration, the bubbles systematically break at the apex while at low concentrations, they break much more randomly because of their greater fragility. I will also show that their lifetime is mainly fixed by the evaporation.
Finally, I will show experiments made at the scale of a foam in a confined cell that allows to visualize all the bubbles (Figure 3). I will show how an image processing can identify all coalescence events, and deduce that the correct parameter to describe the coalescence of a foam is simply the area of soap film available.
First, I will be present the breaking of a soap film during its generation (Figure 1). I will show that their lifetime provides a prediction for the difference in surface tension between the bottom and the top of the film, which is of the order of 1 – 2 mN/m. Then, I will explore the impact of the physicochemicals and of the humidity of the air.
Second, I will focus on surface bubbles (Figure 2), whose rupture localisation depends on the surfactant concentration of the solution. Indeed, at high concentration, the bubbles systematically break at the apex while at low concentrations, they break much more randomly because of their greater fragility. I will also show that their lifetime is mainly fixed by the evaporation.
Finally, I will show experiments made at the scale of a foam in a confined cell that allows to visualize all the bubbles (Figure 3). I will show how an image processing can identify all coalescence events, and deduce that the correct parameter to describe the coalescence of a foam is simply the area of soap film available.