Bursting of particulate films

Yousra Timounay , Elise Lorenceau (1, 2) , Florence Rouyer (1, 2)

1 LPMDI - Laboratoire de Physique des Matériaux Divisés et des Interfaces
2 navier umr 8205 - Laboratoire Navier

When covered with solid particles forming a 2D granular media, free liquid interfaces acquire interesting properties. As the particles concentration increases, a transition from liquid like behavior to solid like behavior is observed [1]. Modifying free liquid interfaces properties is interesting in systems such as foams that undergo aging mechanisms or flow. During all this destabilizing mechanisms, liquid films, which are two interfaces trapping liquid, are subject to high deformation. Former studies have shown the great ability of solid particles to stabilize foams [2]. The aim of our work is to understand the stabilizing mechanisms at the film scale. To do so, we perform two experiments on single films laden with hydrophobic solid particles that can either penetrate the film or stick to the two interfaces depending on particle density and diameter, and the liquid film thickness. On one hand, we study the opening dynamic of a hole in a hexagonal particles laden film, and observe that the opening can expand homothetically or instead a branching fracture can occur depending on the microstructure of the film. On a second hand, we focus on the retraction in a rectangular laden film limited by a mobile stick tracked by surface tension. For high particle coverage rate and large aspect ratio initial state, the sick can be stopped: the film is jammed at its final state. The particle laden film microstructure influences retraction dynamic, as well, while folds are created in almost all the experiments. Moreover, we study the motions of the particles in the dynamic phase using the PIV technique to characterize the rheology of such 2D granular media, in aim to correlate initial state and final state of our experiments. [1] Cicuta, P., Stancik, E. J., & Fuller, G. G. (2003). Shearing or compressing a soft glass in 2D: time-concentration superposition. Physical review letters, 90(23), 236101. [2] Stocco, A., Rio, E., Binks, B. P., & Langevin, D. (2011). Aqueous foams stabilized solely by particles. Soft Matter, 7(4), 1260-1267.

Domaines: Matière Molle [cond-mat.soft]

Yousra Timounay, Elise Lorenceau, Florence Rouyer. Bursting of particulate films. 10th Annual European Rheology Conference- AERC, Apr 2015, Nantes, France. ⟨hal-01143890⟩