POLYSULFONE MEMBRANE HAVING HIGH SELECTIVITY

A spin dope composition produces a polymeric fiber useful in non- cryogenic gas separation. The composition includes polysulfone as the polymeric component,two solvents, in which the polymer is soluble, and a non- sol vent, in which the polymer is insoluble. The solvents preferably include N -methyl -pyrrol i done (NMP) and N,N-dimethyl acetamide (DMAC), and the non-solvent preferably includes triethylene glycol (TEG). Fibers made from the present composition have been found to exhibit superior properties of gas flux and selectivity, as compared with fibers made from spin dopes having only one solvent component. [no suitable figure]