| 摘要 |
Asymmetric membranes for gas separation, made of rigid aromatic polyimides or copolyimides of high selectivity which have as monomers the dianhydride of diphenyldi(trifluoromethyl)methane-3,4,3',4'-tetracarboxylic acid and a monoaromatic meta-diamine or a mixture of monoaromatic meta-diamines. These membranes are manufactured according to a process which includes: - dissolving the polymer in a specific volatile solvent for the polymer, - the application of a film of polymer solution to a support or the extrusion of a polymer solution, - the partial evaporation of the solvent from the film or the tube, placing the film or the tube in contact with a specific coagulant liquid for the polymer solution and drying the coagulated film or tube.
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