Expérimental
Textiles, i.e. woven or non-woven assemblies of natural or synthetic fibers, are ubiquitous in various applications (clothing, paper making, construction, filtration, medicine) but also in many natural systems, such as collagen networks, bird feathers or wall plants. The interaction of fibrous materials with liquids (through adsorption, wetting, drying) is a very common yet complex phenomenon which remains poorly understood. During imbibition, drainage or drying, many liquid-interface appear; the capillary forces associated with these interfaces can locally deform adjacent fibres. These elasto-capillary effects play a role in the wetting dynamics. Moreover many liquids in industrial or natural systems are non-newtonian (saliva, glue, resin, blood, paint, soap etc.). During the internship, we will focus on the simpler case of a drop placed between two rigid or flexible fibres. In particular, we will investigate the effect of the rheological properties on the dynamics of spreading and retracting of drops, as well as the evaporation dynamics. Depending on the student’s interest, different fluids may be investigated: a suspension to see how the concentration in particles will affect the wicking dynamics, the adhesion of the fibers or the evaporation rate of the liquid, an emulsion (e.g. water/oil) where part of the liquid is volatile/non wetting and the other is non volatile/ wetting, or a model non-newtonian fluid, e.g. viscoelastic solutions of polymers.