On the basis of stability analysis of film casting to form membrane

membrane morphology related to hydrodynamic characteristics of the film was studied by computer simulation. It was pointed out that hydrodynamic instability can result in periodic tinevennesses

aggregates and holes on the membrane surface. The effects of excess intermolecular potential energy gradient

gravity

viscosity and surface tension op membrane structure

and the methods to eliminate these structures were discussed. The schlieren observation of the evaporation step of casting solutions was carried out. It was proved that nonhomogeneous and convective structure resulting from hydrodynamic instability would appear in the casting solution during evaporation. Unevennesses

aggregates and holes on the mumbrane surface were observed by optical microscope ana SEM

which corroborated the results of the theoretical analysis.