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Asymmetric gas separation membranes having improved strength

  • US 5,013,767 A
  • Filed: 09/27/1989
  • Issued: 05/07/1991
  • Est. Priority Date: 09/27/1989
  • Status: Expired due to Fees
First Claim
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1. A dope suitable for use in the preparation of an asymmetric, substantially macrovoid-free membrane having potential for gas separation which do is comprised of:

  • (a) an aromatic sulfone polymer; and

    (b) a solvent system being capable of dissolving the hydrophobic polymer in amounts greater than 30% by weight, the solvent system being comprised of;

    (1) two non-solvents, being comprised of a weak non-solvent being a Lewis acid and having a Δ

    σ



    non-solvent-σ

    polymer) of less than about ±

    6 cal0.5 /cm1.5 and a strong non-solvent having a Δ

    σ

    greater than about ±

    6 cal0.5 /cm1.5, the weak non-solvent and the strong non-solvent being present in amounts sufficient to lower the coagulation (g) value to less than about 2;

    (2) one or more solvents being a Lewis base; and

    (3) one or more complexes of solvents being a Lewis acid;

    base complex.

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