| 摘要 |
A gas separation membrane is formed from a copolyimide produced by copolymerization of monomers which include o-tolidine sulfone, at least one other hydrophilic diamine and 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride. One or more additional aromatic dianhydrides can optionally be included. The novel membrane exhibits an excellent combination of high selectivity of gases to be separated from a gas mixture, high permeability a nd strong solvent resistance to hydrocarbon chemicals. The membrane is therefor e useful in separating gases from gas mixtures in which vapor or liquid hydrocarbon contaminants are present, for example in the separation of carbo n dioxide from methane and/or nitrogen in the purification of natural gas.</SD OAB>
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