Composition useful in process for preparing powadir membranes from tetrahalobisphenol a polycarbonates

摘要

The invention is a composition useful for the preparation of POWADIR membranes of a bisphenol-based polycarbonate wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated, wherein the halogen is Cl or Br, the composition comprising (i) a bisphenol-based polycarbonate wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated, wherein the halogen is Cl or Br, (ii) a solvent for such polycarbonate, and (iii) a non-solvent for such polycarbonate. The composition is useful for extruding membranes wherein the membranes formed are POWADIR membranes with a discriminating region capable of separating oxygen from nitrogen. The composition of this invention allows the formation of membranes with excellent physical properties, good separation factors for oxygen and nitrogen, with excellent fluxes.