Modeling the membrane formation of novel PVA membranes for predicting the composition path and their final morphology

Abstract : Herein, a numerical model is developed for investigating the appropriate operating conditions for obtaining porous membranes from PVA/water system. The main interest of such novel polymeric system lies in the use of water as solvent instead of classical organic solvent. In that context, the membrane formation involves three coupled and interdependent phenomena: phase inversion, crosslinking and solvent evaporation. The mass transfer model involves thermodynamic description by Flory-Huggins theory, specific diffusion formalism for dilute system and external mass transfers in free convection. Since the system evolves from monophasic to diphasic region during membrane formation, the diffusion formalisms were adjusted depending on the composition path to simulate the solvent and catalyzer evaporation. The simulations exhibit that due to mass transfers occurring concomitantly to phase inversion and crosslinking, the operating conditions (final temperature, catalyzer, initial solution thickness) must be carefully chosen to ensure the formation of a porous membrane with PVA/water system.