Dynamic Interactions of Nonwovens with Liquids: Experimental, Theoretical and Numerical Investigations

Here, several different scenarios related to the dynamic interaction between liquid and fibrous nonwovens are investigated. First, a physically sound theoretical model of the interaction of viscoelastic fibers with filtration flow of water and the fiber-fiber interactions in the hydroentanglement process is developed in which the number of entanglements between fibers as well as several other characterizations of the process are predicted. Importantly, an optimization targeting smoother surface with reduced jet streaks by using staggered two-row water jet is studied. Second, inspired by the morphology of complex knotted fibers in hydroentanglement, the mutual sliding motion of wrapped filaments, with the dynamic interaction between fibers is investigated. The equations of motions derived for fibers sliding over each other subjected to the Amonton–Coulomb type friction are derived and solved numerically in the framework of the Lagrangian approach, predicting non-trivial fiber evolution. Third, the superhydrophobic electrospun PTFE-SiO2 fibrous membranes with extreme microscopic roughness is fabricated and the dynamic wettability is explored in drop impact experiments mimicking the falling rain, and severe hydrodynamic focusing is demonstrated experimentally and theoretically. The result can be used as the amelioration for the design of fabrication of the waterproof and breathable fibrous membranes (WBFMs) which require the appropriate thickness in a dynamic working condition.