Abstract: Anisotropic fluid separation membranes having an integral discriminating layer are formed from blends of two types of polyimides. The first type is a phenylindane containing polyimide. The second type consists of polyimides formed from the reaction of benzophenone tetracarboxylic dianhydride (BTDA) and optionally pyromellitic dianhydride (PMDA), with toluene diisocyanate (TDI) and/or 4,4'-methylene-bis-phenylisocyanate (MDI). The ratio of Type 1 polymer to Type 2 polymer is 1 or less. The blend membranes are particularly useful for gas separation.

Abstract: Improved fluid separation membranes are prepared from the blends of polyetherimide with phenylindane containing polyimides, wherein the amount of phenylindane containing polyimide in the blend is low. The present invention provides for highly anisotropic membranes particularly useful for gas separation applications and for preparation of composite membranes thereof.

Abstract: A process for producing highly asymmetric hollow fibers useful as permselective gas separation membranes and for producing composite membranes thereof by extruding the spinning dope through a tube-in-orifice spinneret into a gas-filled chamber maintained at reduced pressure and then conveying the extruded hollow fiber through a liquid bath to solidify the extrudate.