Studies on Morphological Structure and Gas Permeability of Graded Density Skinned Asymmetric BCA Membranes

In this paper asymmetric BCA membranes with graded density skin were prepared by dry/wet phase inversion processes. On the basis of SEM observaion of membrane cross-section and gas permeability measurements,three kinds of morphological structures and their gas permeation properties are evidenced in relation to the casting solution which were formed by BCA polymer,solvents and different pore-forming agents. It is found that the transition layer composed of closed-cell with tight and smaller pore-size pores makes the asymmetriC membrane benefit of gas separation. Thus the membrane is effectively decoupled the interdependency between permeability and selectivity.