TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Tetraamine: The tetraamine comprises aromatic tetraamine of formula (1-3).At least one of R1 and R2, R2 and R3, R3 and R4, R1 and R8, and R1 and R4, and at least one of R5 and R6, R6 and R7, R7 and R8, R4 and R5, and R5 and R8 = paired amine groups;X of formula (1) = C or N; andX of formula (3) = a linking group.Preferred Tetraacid Compound: The tetraacid compound comprises aromatic tetraacid such as aromatic tetraacid dianhydride of formula (4) or (5), and bis-ortho-ester-acid halide.X = CH2, C(O), CH(CH3), C(CH3)2, C(CF3)2, C(CH3)Ph, C(Ph)2, or cyclohexyl.Preferred Diamine: The diamine comprises aromatic diamine compound of formula (6).R1 and R3 or R4 = NH2; andRemaining pendant groups = H or 1-12C hydrocarbon.Preferred Amine Composition: The weight ratio of tetraamine to diamine in the amine composition is 5:95-100:0.The amine composition further comprises an aprotic polar solvent, and a base which is tertiary amine for catalyzing the reaction of the tetraacid compound and amine composition.Preferred Process: The tetraacid compound is dissolved in aprotic solvent, when the tetraacid is added to the amine composition. The tetraacid is added to the amine composition in an atmosphere free of oxygen. The reaction of tetraamine, tetraacid compound and diamine produces a polyamide, a polyimide or poly(pyrrolone-imide).The polyamide formed is washed with a solvent, and the polyamide is placed in a mold and heated above 200degreesC so that portions of polyamide is converted to poly(pyrrolone-imide).Preferred Fluid: The fluid comprises a gas stream having 1-4C hydrocarbon and gas, e.g. propylene and propane, nitrogen and oxygen, and carbon dioxide and methane.    TECHNOLOGY FOCUS - POLYMERS - Preferred Membrane: The membrane has maximum olefin-paraffin, permselectivity of 20. Preferably the membrane has propylene-propane permselectivity of greater than 20.The first and second pressure are equal, and second temperature and pressure are greater than first temperature and pressure.The membrane exhibits permselectivity (C) which is less than that of (B).The membrane swells as temperature of membrane is increased, and swelled membrane exhibits greater gas selectivity than unswelled membrane. Preferred Polymer: The poly(pyrrolone-imide) polymer comprises recurring units, and portion of recurring units are represented by formulae (I,II).The ratio of recurring unit (I) to that of unit (II) is 0-1. The poly(pyrrolone-imide) polymer comprises recurring units of formula (III).At least one R = nitrogen atom coupled to another recurring unit, and other R = H or 1-12C hydrocarbon SPECIFIC COMPOUNDS - The tetraacid compound is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FBA). The tetraamine is 1,2,4,5-tetraaminobenzene (TAB). The diamine is 2,4,6-trimethyl-1,3-phenylenediamine (DAM).    EXAMPLE - A separation membrane created using 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FBA)-1,2,4,5-tetraaminobenzene (TAB)/2,4,6-trimethyl-1,3-phenylenediamine (DAM) (6FDA-TAB/DAM (75/25)), showed permeability of 0.498, 15.9 and 73.7 for propane, oxygen and carbon dioxide, respectively. The ideal selectivity of 6FDA-TAB/DAM (75/25) membrane for propane-propylene gas, oxygen-nitrogen gas and carbon dioxide-methane gas were 4.16, 5.16 and 44, respectively. The propane-propylene gas in a ratio of 50:50 when fed at 35degreesC, at feed pressure of 40, 55 and 65 psi to the membrane showed propane permeability of 0.19, 0.79 and 0.85, and selectivity of 4.5, 11.1 and 17.7, respectively. The purge gas of propane and propylene was passed to 6FDA-TAB/DAM (75/25) membrane, and the propane permeability of the membrane at 35 and 55degreesC were 0.498 and 0.686, respectively. The propylene permeability of the membrane at 35 and 55degreesC were 0.120 and 0.043, respectively. The selectivity of the membrane at 35 and 55degreesC were 4.2 and 16.1. The membrane had improved selectivity at higher temperature (of 55degreesC).