Abstract: A fuel deoxygenator includes a plurality of fuel plates defining fuel passages through a housing. A permeable membrane supported by a porous substrate is in contact with fuel flowing through the fuel passages. A vacuum in communication with the porous substrate creates a differential pressure between oxygen within the fuel and the porous membrane. The oxygen partial pressure differential causes oxygen dissolved within the fuel to migrate from the fuel through the permeable membrane away from the fuel. Fuel exiting the outlet includes a substantially reduced amount of dissolved oxygen.

Abstract: Isopycnic or asymmetric mixed matrix hollow fiber membranes for gas separation can be made by a continuous spinning process. Mixed matrix membranes are characterized by a continuous phase of selectively gas permeable polymer in which are uniformly dispersed discrete absorbent particles such as molecular sieves that also have selectivity enhancing properties. The fibers can be monolithic in which the fiber wall is entirely mixed matrix, or composite in which an active mixed matrix layer is positioned adjacent to a supporting substrate layer. The novel mixed matrix hollow fiber membranes provide higher selectivity than dense film membranes of the continuous phase polymer.

Abstract: A process is provided for chemically modifying a dual-layer hollow fibre, wherein the fibre comprises a first layer consisting essentially of a polyimide and a second layer consisting essentially of a polymer which is substantially unaffected by the chemical modification process. The process comprises contacting the polyimide layer with a polyamine. In addition, a process is provided for chemically modifying a polyimide membrane in general, using a process which comprises contacting the membrane with an alcoholic solution of an aliphatic-aromatic polyamine.

Abstract: A gas-liquid separation membrane is provided with high reliability and performance while having gas-permeable pores formed independently of each other in even pore size and in uniform distribution. The gas-liquid separation membrane has a plurality of gas-permeable pores that permit permeation of gas and that prevent permeation of liquid by capillary force, and the plurality of gas-permeable pores are formed independently of each other and in even pore size by laser machining.

Abstract: A polymeric composite may be used for forming fluid separation membranes. The fluid separation membranes may go through a separation selectivity maximum as a function of operating conditions (e.g., temperature and/or pressure). The membranes may be formed from polyamide or poly (pyrrolone-imide). Polyamides may be formed by the condensation of a tetraamine, a tetraacid, and a diamine. Poly (pyrrolone-imides) may be formed by the condensation of a polyamide.

Abstract: Oleophobic and hydrophobic filters for filter venting applications are made by forming a fluorosulfone coating on the surface of a filtration substrate. The filters have high water penetration pressures and high air permeabilities. The coatings are formed by grafting a fluorosulfone oligomer to a polymeric substrate.

Abstract: A process for separating hydrogen from a multicomponent gas mixture containing hydrogen and a hydrocarbon, using gas-separation membranes selective for hydrogen over the hydrocarbon. The membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons.

Abstract: A method for fabricating a composite membrane includes coating a substrate, such as, for example, an asymmetrical porous hollow fiber substrate, with a solution which includes a perfluorinated polymer and a perfluorinated solvent. Prior to coating, the substrate is impregnated with an impregnation fluid which is immiscible with the perfluorinated solvent. The method of the invention further includes removing the perfluorinated solvent and the impregnation fluid. A composite membrane includes a porous asymmetric hollow fiber substrate having an outer surface coated with a perfluoropolymer coating. Separation devices which include composite membranes and methods of separating a fluid mixture into a fraction enriched in a first component and a fraction depleted in that component also are described.

Abstract: A hollow fibre membrane has an active layer (2) in which elongate polymer molecules (3) are longitudinally aligned essentially parallel to the extrusion direction to thereby define a plurality of spaced free volume cavities (4) which are particularly numerous and are essentially regularly spaced to provide enhanced selectivity when used in gas separation. The hollow fibre membrane is manufactured using a dry/wet phase separation process by spinning a dope composition which is extruded through a spinneret (12) having an annulus or annular orifice (16) together with a bore-forming fluid or coagulant. The dope composition has a power law index of less than 1 (unity) and the bore coagulant has a water activity of less than 1 (unity).

Abstract: A process for preparing polyimide gas separation membranes is disclosed. The process involves preparing polyamic acid salt membrane precursors that are converted into polyimide membranes by mild thermal or chemical treatments. The gas separation processes that utilize these polyimide membranes are further disclosed.

Abstract: In an arrangement for removing water vapor from pressurized gases or gas mixtures, particularly from air, a membrane separating apparatus is provided wherein the gas-vapor stream is separated into a vapor-enriched permeate stream and a vapor-depleted retentate stream and the vapor enriched permeate stream is conducted to a vacuum pumping device for generating at the permeate side of the membrane separating apparatus a vacuum providing for a predetermined trans-membrane pressure ratio.

Abstract: A membrane separation process and apparatus for carrying out the process involves contacting a gas feed mixture with one side of a selectively gas permeable membrane and allowing the components to pass through the membrane to form a permeate composition in contact with the opposite side of the membrane and leave a retentate composition on the feed side of the membrane. The process includes introducing a sweep flow of feed gas into the permeate composition near the membrane at a rate effective to increase the enrichment of the retentate composition in the less preferentially permeable component of the feed mixture to a concentration much greater than is achieved without the sweep flow. This process is especially well suited to improve single stage membrane separation effectiveness so that the need for conventional multistage separations to achieve moderate to high purity retentate compositions can be obviated.

Abstract: A solid state facilitated transport separation membrane prepared by forming a polymer electrolyte layer consisting of a polymer and a metal salt to a porous membrane having good permeance and mechanical strength; the polymer electrolyte facilitated transport separation membrane thus prepared is characterized in that the permeance and selectivity to alkene hydrocarbons is high, and that the complex is formed by a polymer ligand and a metal in the polymer electrolyte maintains its activity as a carrier of alkene even under dry operation.

Abstract: The invention relates to sulphonated polyimides, notably of formula (I) The invention also relates to an ion exchange membrane that includes such a polyimide and a fuel cell that includes such a membrane. The membranes of the invention have excellent durability and low cost and the fuel cells can be used, in particular, in electric vehicles.

Abstract: The process is characterised by sulfonating a partially brominated poly(phenylene oxide). The gas separation material so formed may be made into a membrane and is useful in separating component gases from a gas mixture.

Abstract: A filter element comprises a substrate constructed from at least two different materials. A first one of the materials has a first temperature at which the first material activates. A second one of the materials is at least a partially crystalline structure and has a second temperature which is lower than the first temperature at which the second material activates. A porous membrane is supported by the substrate. An attachment is between the substrate and the membrane. The attachment results from the second material of the substrate activated at a temperature less than the first temperature to engage portions of the membrane at spaced apart locations and fix together the membrane and the substrate upon the second material cooled to a temperature less than the second temperature.

Abstract: The separation factor with respect to a gas binary of a selectively gas permeable membrane of a fluoropolymer can be increased by fabricating the membrane from a composition of a blend of the fluoropolymer with a nonfugitive, nonpolymeric fluorinated adjuvant. The composition can be made by dissolving the adjuvant and the polymer in a suitably compatible solvent then forming the membrane from the solution for example by casting, dipping, or spraying the solution on a substrate and devolatilizing the solvent. The extent of the selectivity increase varies widely with the combination of fluoropolymer and adjuvant and largely increases in direct relation with the proportion of adjuvant in the membrane composition.

Abstract: Improved polymer blends, and polymer blend membranes having improved mechanical properties are provided by alteration of the critical solution temperature of the polymer blend spinning solution through the incorporation of organic or inorganic complexing agents.

Abstract: The invention relates to a method of making an epoxysilicone coated membrane by coating a porous asymmetric membrane layer with a UV-curable controlled release epoxysilicone coating. A mixture of the epoxysilicone resin and an onium photocatalyst are applied to the porous asymmetric membrane layer in a dilute non-polar solution and cured by UV or electron beam radiation to produce a dry epoxysilicone coated membrane. The porous asymmetric membrane layer is comprised of an asymmetric cellulosic membrane or an asymmetric polymer membrane with a low selectivity. The epoxysilicone coating was found to provide the asymmetric membrane layer with improved selectivity which extends to separation temperatures below 70° C. and provides stable flux rates. Membranes produced in this manner are useful for the separation of gases such as carbon dioxide from natural gas.

Abstract: The present invention provides a compact and inexpensive air-permeable cap and an outdoor lamp, automobile lamp and automobile electrical component including such an air-permeable cap. A novel air-permeable cap is provided including a closed-end cylindrical cover member, a substantially cylindrical body fitted in the closed-end cylindrical cover member, and an air passage formed between the inner wall of the closed-end cylindrical cover member and the outer wall of the substantially cylindrical body and between the bottom surface of the closed-end cylindrical cover member and the lower end of the substantially cylindrical body, wherein the mounting portion at which the air-permeable cap is mounted on the mounting opening of the housing is formed at the top of the substantially cylindrical body.

Abstract: The present invention is a bi-thermal membrane process for separating and recovering hydrogen isotopes from a fluid containing hydrogen isotopes, such as water and hydrogen gas. The process in accordance with the present invention provides counter-current cold and hot streams of the fluid separated with a thermally insulating and chemically transparent proton exchange membrane (PEM). The two streams exchange hydrogen isotopes through the membrane: the heavier isotopes migrate into the cold stream, while the lighter isotopes migrate into the hot stream. The heavy and light isotopes are continuously withdrawn from the cold and hot streams respectively.

Abstract: A filter medium for filters wherein the evolution of organic gases and dusting from a reinforcing member are depressed and thus the excellent characteristics inherent to a porous polytetrafluoroethylene membrane as a collection layer are fully achieved. The filter medium (1) for filters comprises a porous polytetrafluoroethylene membrane (2) and a porous ultrahigh-molecular weight polyolefin membrane (3) as a reinforcing member for the filter medium.

Abstract: An apparatus for degassing liquids comprises a cavity through which liquid is conducted, with gas being removed from the liquid through at least one of the limiting faces of the cavity by providing on the side of the face distal to the cavity a smaller pressure than within the cavity. The apparatus is characterized in that the limiting face between the cavity and the region having reduced pressure compared to the cavity is formed by at least one thin membrane, having a thickness of less than about 10 micrometers, and in that a porous support structure for supporting the membrane is provided. The degasser can be miniaturized and integrated into a liquid chromatograph.

Abstract: A multi-phase solid electrolyte ion transport membrane comprising at least two phases wherein one of the phases comprises an oxygen ion single conductive material, or a mixed conductor. The other phase comprises an electronically-conductive metal or metal oxide that is incorporated into the membrane by deposition of the metal or metal oxide from a polymer made by polymerizing a chelated metal dispersion in a polymerizable organic monomer or prepolymer. The multi-phase composition advantageously comprises a first phase of a ceramic material and a second phase of a metal or metal oxide bound to a surface of the ceramic material. The multi-phase composition is advantageously prepared in an in-situ fashion before fabricating the membrane matrix. As another alternative, a preformed ceramic matrix is surface-coated with a metal or metal oxide.

Abstract: A spiral wound type membrane element is formed by superposing gas-liquid contact membranes on both surfaces of a first fluid passage forming member, superposing a second fluid passage forming member on the surface of one of the gas-liquid contact membranes and spirally winding the gas-liquid contact membranes around a second fluid supply pipe along with the first fluid passage forming member and the second fluid passage forming member. A side portion on the inner peripheral side and a side portion on the outer peripheral side of a first fluid passage formed by the first fluid passage forming member between the gas-liquid contact membranes are sealed. Both end portions of a second fluid passage formed by the second fluid passage forming member between the gas-liquid contact membranes are sealed. The spiral wound type membrane element is stored inside a cylindrical container. The gas-liquid contact membranes are formed by PTFE (polytetrafluoroethylene) porous membranes having hydrophobicity.

Abstract: An adsorbent filter including compression molded particulate adsorbent construction is provided. The compression molded particulate adsorbent construction contains a particulate adsorbent and a sufficient amount of binder to retain the particulate adsorbent in a non-free flowing form. The adsorbent filter preferably includes a compression molded particulate adsorbent construction as described, positioned within an outer, porous cover. Preferably the outer, porous cover includes expanded porous polytetrafluoroethylene. In certain preferred applications, the adsorbent filter is positioned within a housing defining an internal volume and including therein electronic component(s), such that the adsorbent filter protects the internal volume of the housing, and components therein, from damage. The typical application is as a disk drive adsorbent filter. A preferred method for preparing an adsorbent filter according to the present invention is provided.

Abstract: A portable breathing air supply apparatus uses a membrane separation module to obtain oxygen enriched air from ambient air which is blown into the module by an electrically powered fan. Oxygen enriched air is withdrawn from the permeate side of the membrane by a vacuum pump and is stored in a reservoir while the user exhales. In a preferred mode, a conserver valve in a tube leading from the reservoir to the user's mouth or nose is triggered to feed the enriched air for a preselected duration after a sensor in the tube detects onset of inhalation. Power for the electrical components can be supplied by batteries. The portable apparatus is sufficiently compact and light to be transported by persons weakened by certain chronic breathing disorders, such as chronic obstructive pulmonary disease and emphysema, and thus frees the user to roam for long periods away from a primary source of oxygen.

Abstract: A filter element is adapted to be located in a gas stream. The filter element comprises a substrate having a structure selected from the group consisting of scrimed needled felt, scrimless needled felt, woven fabric and mesh. The substrate comprises at least two different materials. A first one of the materials has a first melting temperature. A second one of the materials has a second melting temperature lower than the first melting temperature. An expanded polytetrafluoroethylene filtering membrane is adapted to be located upstream relative to the substrate in the gas stream and supported by the substrate. The substrate is attached to the filtering membrane by the second material of the substrate melted to engage the membrane and fix the membrane to the substrate.

Abstract: Watertight sealed type electric motor 10, with a clearance between a core wire and a cover 24 of a lead wire 20, which is a vent path between the interior of the motor 10 and the outside, which clearance is covered a vent filter 28, which permits only gas to pass therethrough, and is attached to the lead wire 20 so as to cover an opening end portion of the cover 24.

Abstract: This invention relates to a miniaturizable separation module (dehumidifier, humidifier) utilizing the gas separation property of waterproof membranes having fine moisture-permeable through holes. The separation module according to the invention comprises: a cylindrical casing 10 installed at the wall of a moisture-proof and drip-proof box 4, so as to form a gas passage communicating the inside and the outside of the box; a plurality of waterproof membranes 1, 2, 3, having fine moisture-permeable through holes, disposed in the cylindrical casing at intervals of spacing, so as to form chambers 5, 6 in the gas passage; and conductive porous structures disposed in proximity of the waterproof membranes. The longitudinal section of the solid portion around the holes of the conductive porous structure is formed into an essentially egg-like shape, and the acute angle side of the egg-like longitudinal sectional shape is disposed so as to direct to the waterproof membrane.

Abstract: A fine powder of polytetrafluoroethylene is mixed with a liquid lubricant, and the mixture is molded into an unsintered sheet by at least one of an extrusion method and a rolling method. The liquid lubricant is removed from the sheet by at least one of a heating method and an extrusion method. This sheet-form molding is stretched in the machine direction to produce a sheet-form polytetrafluoroethylene molding which, upon analysis with a differential scanning calorimeter, gives a crystal fusion curve having an endothermic peak in the temperature range of 345.+-.5.degree. C. and which has a degree of crystallization of from 0.1 to 0.85 and a specific gravity of 1.4 or lower. The molding is then stretched in the transverse direction to produce a porous polytetrafluoroethylene (PTFE) membrane. The process is effective in producing, with good reproducibility, a useful porous PTFE membrane which has a high collection efficiency and a low pressure loss and is reduced in the leakage of coarse particles.

Abstract: Separation membranes excellent in strength, durability, heat resistance and solvent resistance as well as in balance between substance separation properties and substance permeability are disclosed, which are formed from polyhydrazidoimide resins, and preferably comprises a non-porous dense layer formed from a polyhydrazidoimide resin obtained from the reaction of an aromatic tetracarboxylic dianhydride such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and an aromatic dihydrazide such as isophthalic dihydrazide as essential components.

Abstract: A novel polyimide having a repeating structure unit expressed by the following general formula (1), a method for manufacturing the same, a gas separation membrane using the novel polyimide and the method for manufacturing the same. The gas separation membrane using this polyimide is excellent in gas permeable performance and separation selectivity for gas, for example, carbon dioxide, methane, etc.General Formula (1) ##STR1## where R denotes a quadrivalent organic group.

Abstract: A supported gas separation membrane for separating a particular component from a mixture of gases, a process for its manufacture and the use of the membrane in the separation of gases are provided in which the supported gas separation membrane comprises (a) a porous polymeric support layer and (b) an asymmetric gas separation membrane layer formed from a polyimide having repeating units of the general formula: ##STR1## wherein R is: ##STR2## and x is an integer.

Abstract: In one aspect, a method for selectively removing at least one target component from a multicomponent feed fluid using a removal system, the system including a feed chamber having an inlet and an outlet, a permeate chamber, and a membrane for separating the feed and permeate chambers. The membrane is selective for the at least one target component.

Abstract: The invention provides for gas separation membranes with superior gas transport properties made from certain two- and three-component blends of polyethersulfone with aromatic polyimides, to provide a gas separation membrane with superior productivity and good selectivity.

Abstract: Disclosed are a first vent filter member which includes: an elastomer member made of a thermoplastic elastomer to which a water-repellent film can be fixed by fusion and having a cylindrical form whose one end part serves as an opening for insertion of a mounting part of a base; a water-repellent film thermally fusion-bonded to the other end part of the elastomer member; and a covering cap which protects the water-repellent film and has been fitted and fixed to the elastomer member in such a manner that a vent passageway is formed between the elastomer member and the covering cap, and a second vent filter member which includes: an elastomer member made of a thermoplastic elastomer to which a water-repellent film can be fixed by fusion and having a disk form which has on one side thereof a tapered insertional part to be inserted into a mounting part, is blocked on the other side with a mist barrier cover, and has a sealing/fixing part on the outer periphery thereof and a vent passageway extending from said one

Abstract: A deaeration assembly for removal of air or other gases dissolved in a liquid. The assembly includes a deaeration element having a gas-channel-forming component enclosed and sealed within an envelope which includes a nonporous fluoropolymer film. The assembly also includes a liquid-channel-forming component which can be positioned on the outside of the element, or can be enclosed with the gas-channel-forming component within the element. The assembly can be formed in spiral-wound or folded configurations for installation in a deaeration module or apparatus. The deaeration assembly is useful for removal of gases dissolved in chemically aggressive liquids, high-purity liquids, and other special liquids.

Abstract: A polyimide resin semipermeable membrane has a continuous structure of a homogeneous skin layer part having an average thickness of 5-1000 nm and a porous layer that is made of the same materials and has the same thickness as the skin layer. The porous layer is formed by the void structure having the average hole diameter of less than 3 .mu.m so that a gas separation membrane can be provided, having high permeability and satisfying cost efficiency requirements can be provided. The above-mentioned membrane is formed by the following steps: a solution is made by adding diethylene glycol dimethyl ether into polyimide; the obtained solution is left for deaeration and adjusted; the film-forming solution is cast on a polyester nonwoven cloth, which serves as a supporting layer, with an applicator; the solution is soaked in water as a solidifying solution for 5 minutes and in a water. Thus semipermeable membrane comprising the homogeneous skin layer part and the porous layer.

Abstract: An adsorbent filter including compression molded particulate adsorbent construction is provided. The compression molded particulate adsorbent construction contains a particulate adsorbent and a sufficient amount of binder to retain the particulate adsorbent in a non-free flowing form. The adsorbent filter preferably includes a compression molded particulate adsorbent construction as described, positioned within an outer, porous cover. Preferably the outer, porous cover includes expanded porous polytetrafluoroethylene. In certain preferred applications, the adsorbent filter is positioned within a housing defining an internal volume and including therein electronic component(s), such that the adsorbent filter protects the internal volume of the housing, and components therein, from damage. The typical application is as a disk drive adsorbent filter. A preferred method for preparing an adsorbent filter according to the present invention is provided.

Abstract: This invention relates to a method of an apparatus and method for separating component gases in a gas mixture employing a glassy polymer membrane at temperatures at or slightly above the freezing point of any liquid present so as to achieve superior separator of gas components. The composition of certain monomers and polymers are claimed.

Abstract: A deaeration assembly for removal of air or other gases dissolved in a liquid. The assembly includes a deaeration element having a gas-channel-forming component enclosed and sealed within an envelope formed of a non-porous fluoropolymer film. The assembly also includes a liquid-channel-forming component which can be positioned on the outside of the element, or can be enclosed with the gas-channel-forming component within the element. The assembly can be formed in spiral-wound or folded configurations for installation in a deaeration module or apparatus. The deaeration assembly is useful for removal of gases dissolved in chemically aggressive liquids, high-purity liquids, and other special liquids.

Abstract: The present invention provides a process for preparing membranes using novel silicon containing polyarylates of Formula I ##STR1## where R.sub.1 to R.sub.8 represent hydrogen, alkyl groups containing 1 to 5 methylene group or halogen atoms, R.sub.9 and R.sub.10 represents alkyl groups containing 1 to 5 carbon atoms or CF.sub.3 group and R.sub.11 and R.sub.12 represent alkyl groups with 1 to 5 carbon atoms or phenyl groups.

Abstract: Gas separation membranes having enhanced selectivity for a mixture of gases is disclosed. The membranes may be asymmetric or multicomponent. The membranes surprisingly provide selectivity for gases in a mixture that approaches the relative selectivity of the single gas components. Preferably the membrane provides selectivity for a mixture of gases which is at least 65%, preferably 80%, of the relative selectivity of the corresponding single gases. A process for making improved gas separation membranes is also disclosed.

Abstract: A fluorine-containing polyimide gas separation membrane which is pinhole-free, uniform over a large area, and has a high permeability and a high separation factor .alpha. is provided. A polyimide resin is dissolved in at least one solvent selected from the group consisting of an organic solvent (A) or (B). The organic solvent (A) has a dielectric constant of 30 or less and a dipole moment of 3.0 D or less. The organic solvent (B) mainly contains an organic solvent having at least one ether bonding in the molecular unit. In the next step, the polyimide resin is dipped in a solvent (C) in order for desolvation. The solvent (C) does not dissolve the fluorine-containing polyimide resin while it is miscible with the organic solvent (A) or (B). As a result, an asymmetric gas separation membrane is formed. The fluorine-containing polyimide resin layer comprises a skin layer the thickness L.sub.1 thereof is about 40 nm and a sponge like layer the thickness L.sub.2 thereof is about 30 .mu.m.

Abstract: A membrane filter comprises a membrane provided with pores with a pore size between 5 nm and 50 .mu.m. The membrane may easily and reliably be processed with use of silicon micromachining through depositing a relatively thin membrane layer on a support, by use of a suitable vapour deposition or spincoating technique, after which perforations are made in the thin membrane layer, for example by etching with aid of photo-lithography or an imprint technique. Such a membrane is very well applicable for the separation of biological cells. A membrane with a thickness smaller than the diameter of the perforations is in particular suited for the separation of vulnerable cells and may be used as a leucocyte filter or as a blood plasma separator of blood concentrates. A microfiltration membrane according to the invention may very well be applied as a support for the deposition of a separation layer for ultrafiltration, gas separation or catalysis.

Abstract: A device and method for selectively removing one or more components from a multicomponent gas/vapor mixture by membrane fractionation. The membrane fractionation gas removal system preferably comprises: a feed chamber which contains the gas/vapor mixture; at least one porous membrane having a first side which contacts the gas/vapor mixture in the feed chamber, and a second side; at least one nonporous membrane having a first side which contacts the second side of the at least one porous membrane, and a second side, the nonporous membrane having a permeability selective to one or more components; an exit chamber connected to the second side of the at least one nonporous membrane such that the component exiting the nonporous gas enters the exit chamber; and an evacuation member connected to the exit chamber for evacuating one or more components from within the exit chamber.

Abstract: An apparatus (10) and a method are described for extracting gas from a liquid containing dissolved gas. The liquid is pumped from an external reservoir (40) of the liquid into a separation cell (14) by a liquid-pumping chamber (11). In separation cell (14) a permselective membrane (17) effects extraction of the dissolved gas from the liquid. A gas-pumping chamber (23) pumps the extracted gas from the permeate chamber (16) of the separation cell (14) to a collection station (27), where the extracted gas can be analyzed, separated into its individual components, or stored, as desired.

Abstract: Novel polyimide gas separation membranes and the process of using such membranes to separate gases are disclosed. The polyimides are formed from rigid aromatic dianhydrides and aromatic diamines that contain sulfonic acid, salified sulfonic acid, or sulfonic ester groups. Methods of preparing improved composite gas separation membranes from the sulfonated polyimides of this invention are disclosed.

Abstract: Useful gas separation membranes made from aromatic polyimides which comprise pendant nitro groups incorporated onto the phenyl backbone of the polymer. These polymers may be synthesized by the aryl nitration of the unsubstituted polyimides, or from the condensation reaction of aromatic diamines containing pendant nitro groups with aromatic dianhydrides, and are particularly useful in air separation.