(US5055114-A)      Gas sepn. membranes comprise a thin layer of a polyester or copolyester derived from the reaction of (a) an aromatic dicarboxylic acid or its deriv. and (b) more than 50 mole% of a tetrabromobisphenol of formula (I). (a) comprises: (1) 80 mole% or more of isophthalic acid or its dichloride and/or 4-bromo-isophthalic acid or its dichloride; and (2) 20 mole% or less of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or its dichloride.    Alternatively it comprises: (1) 30 mole% or less of isophthaloyl dichloride and/or 4-bromoisophthalic acid or its dichloride; and (2) 70 mole% or more of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or its dichloride. The membrane has high selectivity and permeation rate values for O2/N and CO2/CH4 sepns.    In (I) R = gp. (II) or divalent cyclododecyl.    (13pp)    (JP94061435-B2)      Gas sepn. membranes combining high selectivity (S) and high permeation rate values (P) for O2/N2 and CO2/CH4 sepns. comprise a thin layer of a (co)polyester derived essentially from reaction of an aromatic dicarboxylic acid component (A) and a diol component (B). (B) comprises more than 50 mole.% of a tetrabromobisphenol of formula (I); R' = C(CF3)2 or divalent cyclododecyl, and X = Br. (A) comprises (i) isophthalic acid (IPA) and/or 4-bromoisophthalic acid (BIPA), with (ii) terephthalic acid (TPA) and/or 2-bromo-terephthalic acid (BTPA); or the corresp. dihalides. Proportions (mole.%) of (i):(ii) are (a) at least 80:20, or (b) 30:70 or less. The balance of (B), if any, pref. consists of cpds. of formula (I) where X = CH3 or Cl.    USE/ADVANTAGE -   The membranes may be composite, asymmetric, homogeneous or isotropic and may be constructed in any of the conventional forms e.g. sheet or tube, etc. They are partic. efficient at sepg. O2 from N2 (S = 5.6-7.2, and P = 4.7-11.8 Barrers at ambient temp.), and CO2 from CH4 (S at least 30; P at least 15).    (SU1836128-A3)      Gas sepn. membranes combining high selectivity (S) and high permeation rate values (P) for O2/N2 and CO2/CH4 sepns. comprise a thin layer of a (co)polyester derived essentially from reaction of an aromatic dicarboxylic acid component (A) and a diol component (B). (B) comprises more than 50 mole.% of a tetrabromobisphenol of formula (I); R' = C(CF3)2 or divalent cyclododecyl, and X = Br. (A) comprises (i) isophthalic acid (IPA) and/or 4-bromoisophthalic acid (BIPA), with (ii) terephthalic acid (TPA) and/or 2-bromo-terephthalic acid (BTPA); or the corresp. di-halides. Proportions (mole.%) of (i):(ii) are (a) at least 80:20, or (b) 30:70 or less. The balance of (B), if any, pref. consists of cpds. of formula (I) where X = CH3 or Cl.    USE/ADVANTAGE -   The membranes may be composite, asymmetric, homogeneous or isotropic and may be constructed in any of the conventional forms e.g. sheet or tube, etc. They are partic. efficient at sepg. O2 from N2 (S = 5.6-7.2, and P = 4.7-11.8 Barrers at ambient temp.), and CO2 from CH4 (S at least 30; P at least 15).    (JP96004729-B2)      Gas sepn. membranes combining high selectivity (S) and high permeation rate values (P) for O2/N2 and CO2/CH4 sepns. comprise a thin layer of a (co)polyester derived essentially from reaction of an aromatic dicarboxylic acid component (A) and a diol component (B). (B) comprises more than 50 mole.% of a tetrabromobisphenol of formula (I); R' = C(CF3)2 or divalent cyclododecyl, and X = Br. (A) comprises (i) isophthalic acid (IPA) and/or 4-bromoisophthalic acid (BIPA), with (ii) terephthalic acid (TPA) and/or 2-bromoterephthalic acid (BTPA); or the corresp. dihalides. Proportions (mole.%) of (i):(ii) are (a) at least 80:20, or (b) 30:70 or less. The balance of (B), if any, pref. consists of cpds. of formula (I) where X = CH3 or Cl.    USE/ADVANTAGE -   The membranes may be composite, asymmetric, homogeneous or isotropic and may be constructed in any of the conventional forms e.g. sheet or tube, etc. They are partic. efficient at sepg. O2 from N2 (S = 5.6-7.2, and P = 4.7-11.8 Barrers at ambient temp.), and CO2 from CH4 (S at least 30; P at least 15).    (EP376234-B2)      Gas sepn. membranes combining high selectivity (S) and high permeation rate values (P) for O2/N2 and CO2/CH4 sepns. comprise a thin layer of a (co)polyester derived essentially from reaction of an aromatic dicarboxylic acid component (A) and a diol component (B). (B) comprises more than 50 mole.% of a tetrabromobisphenol of formula (I); R' = C(CF3)2 or divalent cyclododecyl, and X = Br. (A) comprises (i) isophthalic acid (IPA) and/or 4-bromoisophthalic acid (BIPA), with (ii) terephthalic acid (TPA) and/or 2-bromoterephthalic acid (BTPA); or the corresp. dihalides. Proportions (mole.%) of (i):(ii) are (a) at least 80:20, or (b) 30:70 or less. The balance of (B), if any, pref. consists of cpds. of formula (I) where X = CH3 or Cl.    USE/ADVANTAGE -   The membranes may be composite, asymmetric, homogeneous or isotropic and may be constructed in any of the conventional forms e.g. sheet or tube, etc. They are partic. efficient at sepg. O2 from N2 (S = 5.6-7.2, and P = 4.7-11.8 Barrers at ambient temp.), and CO2 from CH4 (S at least 30; P at least 15).