Abstract: A process for the preparation of anisotropic hollow fibers useful as permselective separation membranes and for producing composite membranes thereof, involves extruding a spinning dope through a spinneret that extends into a coagulation chamber maintained at subatmospheric pressure, conveying the nascent hollow fiber through a column that extends into the reduced pressure chamber, and contains at least two different abutting liquids arranged in sequence. An apparatus for conducting the process includes the vacuum chamber, the spinneret and the column that extends into the vacuum chamber and is equipped with entrance and exit ports for introduction and removal of at least two abutting liquid coagulation media.

Abstract: The present invention is related to a composite microporous polyolefin membrane having a high separation, a high flux and a high strength, comprising a microporous layer, b-layer, providing a reinforcing function, the b-layer being stacked on at least one surface of a microporous layer, a-layer, providing a separate function, wherein micropores in a-layer and b-layer are mutually interconnected inside of the layer and also between layers, thereby forming micropores connected from one surface of the membrane to the other surface thereof, and the ratio of the mean distance Da between microfibril bundles of micropores existing in a-layer to the mean distance Db between microfibril bundles of micropores existing in b-layer is in the range of 1.3.ltoreq.Db/Da.ltoreq.15, and furthermore all of the inner and the outer surfaces of the composite membrane and the surface inside of micropores are coated by a thin film of a hydrophilic copolymer.

Abstract: Products and methods for controlling the porosity and permeation of a web are provided using a curable thixotropic shear thinnable polymer composition that preferably encapsulates a plurality of fibers of the web and/or forms an internal layer within the web. Webs suitable for several different uses are featured, for example medical garments resistant to permeation by a virus or bacteria. The effective pore size of the web is controlled by regulating various factors such as the thickness of the polymer composition encapsulating the fibers and the thickness and placement of the internal polymer layer. Other factors include the polymer density, structure, and crosslinking orientation, as well as the diffusion, permeation and sorption of the polymer.

Abstract: The microfiltration membrane cartridge filter is formed by pleating a porous membrane sheet having a mean pore size of 0.05 to 10 .mu.m, rounding the sheet in the form of a cylinder, liquid-tightly sealing joints of the rounded sheet and liquid-tightly sealing opposite ends of the cylinder by end plates, wherein pores in the opposite end portions of the cylindrical pleated membrane are filled up with a high molecular-weight polymer to reject the liquid-permeation of the opposite end portions of the cylindrical pleated membrane. The microfiltration membrane cartridge filter can be made wet to water easily so that an integrity test for the filter is carried on easily.

Abstract: The present invention relates to the field synthetic polymeric membrane materials formed from casting polyvinylidene difluoride (PVDF) polymer solutions and/or dispersions. Membranes formed in accordance with the present invention are all highly porous. Both internally isotropic membranes and highly asymmetric PVDF membranes are disclosed. The membranes of the invention are useful in a variety of microfiltration and ultrathin applications.

Abstract: The invention relates to a semipermeable composite membrane comprising a microporous substrate provided with a semipermeable microporous substrate membrane which is provided, on at least one side, with a water-permeable polymer layer, said polymer layer containing the interfacial-polymerization product of an amine-terminal dendrimer and a compound polymerizing therewith. According to the invention, the amine-terminal dendrimers used, are poly(alkylene imine) dendrimers. These dendrimers preferably have terminal primary and/or secondary amine groups. In particular, use is made of a 1,4-diaminobutane ?4!: (1-azabutylidene).sup.x-4 : propylamine or propyl-N-alkyl-amine, wherein x=4, 8, 16, 32 or 64. Expediently, the compound which polymerizes with the dendrimer is selected from the group consisting of a carboxylic acid or carboxylic acid derivative, a sulphonic acid or sulphonic acid derivative, and an isocyanate compound.

Abstract: A method for forming a reactive medium for removing homogeneous and heterogeneous impurities from a fluid is provided. The method includes forming a uniform oxide layer, depositing at least one layer of carbon, depositing a precursor metal species, and heating a substrate having the layer including carbon.

Abstract: A composite porous membrane is provided which comprises a porous membrane substrate having an average pore size between 0.01 and 10 microns formed of a first polymer which is coated over its entire surface with a crosslinked second polymer. The second polymer is dissolved in a solvent with a free radical polymerization initiator in the absence of a crosslinking agent. The second polymer is crosslinked in situ and rendered insoluble by mild heating and/or exposure to ultraviolet light.

Abstract: Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing, fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior, porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor, converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by, e.g., burning, the silica remains and the ceramic is easily rewaterproofed.

Abstract: Disclosed are methods for increasing the ability of a porous hydrophobic substrate to transmit aqueous liquids by applying to a hydrophobic substrate selected polyether modified polydimethylsiloxanes. Further, disclosed are coated substrates prepared by the described methods.

Abstract: A composite membrane is disclosed which operates as a filter for liquids, solids and gases and combinations thereof, having high permeability for the filtrate, e.g., nitrogen passing therethrough, and high selectivity for matter retained thereby, e.g., volatile organic compounds, so that the N.sub.2 /VOC selectivity is at least about 50/1 or greater; prepared by a low pressure chemical vapor deposition process comprising: (a) providing as a first component thereof, a mesoporous membrane substrate having pore diameters greater than about 20 .ANG.

Abstract: A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

Abstract: A composite hollow fiber membrane is provided, which includes a microporous hollow fiber support membrane and a polymeric ultrathin layer formed on the outer surface of the microporous hollow fiber support membrane by interfacial polymerization, and which contains an organic fluorine compound. Also provided is a process for its production, in which a microporous hollow fiber support membrane is successively contacted with first and second solutions involved in the polymerization, but it is further contacted with a third liquid which is substantially immiscible with the first and/or second solutions and which contains an organic fluorine compound, before and/or after contact with the second solution. Thus, it becomes possible to produce a composite hollow fiber membrane exhibiting excellent permeability and selectivity performance in a continuous and stable manner.

Abstract: Inorganic membranes such as zeolite membranes or other molecular sieve membranes can be provided by using silicone polymer material as starting material. A thin film zeolite membrane or a thin film membrane formed of interlocking zeolite crystals can be provided. Water soluble or water insoluble silicones can be treated in a basic solution under conditions and with an appropriate structure directing template, suitable aluminum content and at a temperature that is appropriate for growing a desired inorganic crystal framework. The membranes can be formed across the perforation of a support, such as a steel screen.

Abstract: A thin fluoropolymer film is covalently bonded to a microporous ptfe film to make a bilayer for separation, filtration or reverse osmosis, by exposing the microporous film to perfluorocyclohexane under plasma. The perfluorocyclohexane molecules undergo scission and the fragments combine on the substrate to make a fluoropolymer film wherein the pores of the substrate have not been completely closed by the coating.

Abstract: A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

Abstract: This invention pertains generally to aging methods suited to aerogel thin film fabrication, and particularly to techniques for improving gel strength and/or aerogel dielectric constant by a rapid aging technique, which avoid damage or premature drying of wet gel thin films during aging. A substrate having a wet gel thin film deposited thereon is contacted with a saturated water vapor atmosphere, preferably at an elevated pressure and a temperature greater than 100.degree. C. The method may comprise a vapor-phase exchange step to remove low boiling point pore liquids such as ethanol prior to or during aging. The method may also comprise a vapor-phase exchange step to replace water in the wet gel with another pore liquid such as acetone to stop the aging process and prepare the wet gel for drying. A vapor-phase aging catalyst (e.g. ammonia) may also be used to enhance the aging process.

Abstract: The present invention relates to a continuous gastight film of zeolites on a porous underlayer, a zeolite membrane obtainable by calcining the gastight zeolite film, and a module with such a gastight zeolite film, which module consists of a membrane housing and a supported membrane, the whole of membrane housing and supported membrane being composed of not more than two materials.

Abstract: The present invention provides an isotropic, skinless, porous, polyvinylidene fluoride membrane having a K.sub.UF of at least about 15 psi (103 kPa), and preferably below about 50 psi (345 kPa), when tested using liquid pairs having an interfacial tension of about 4 dynes/cm (4 mN/m). The present inventive membrane preferably has a titer reduction of at least about 10.sup.8 against T.sub.1 bacteriophage, more preferably also against PR772 coliphage, and even more preferably also against PP7 bacteriophage. The present inventive membrane can have a thickness of about 20 mil (500 .mu.m) or less and even as low as about 5 mil (125 .mu.m) or less. The present invention also provides a method of preparing such a membrane by providing a casting solution comprising polyvinylidene fluoride and a solvent therefor, heating the casting solution to a uniform temperature of about 57.degree. C. to about 60.degree. C.

Abstract: Disclosed is a method for producing a composite reverse osmosis membrane comprising the steps of coating a porous support with (A) a solution containing a compound having at least two reactive amino groups per molecule and bringing (B) a solution containing a polyfunctional acid halide into contact with the solution (A) to induce crosslinking to form a crosslinked polyamide skin layer, in which the crosslinking is carried out in the presence of a substance having a solubility parameter of 8 to 14 (cal/cm.sup.3).sup.1/2. The resulting composite reverse osmosis membrane exhibits high salt rejection and high water permeability.

Abstract: Non-evaporative processes for coating ion-containing polymers onto selected substrates and the articles made thereby, which processes fundamentally comprise contacting a substrate with a dispersion or solution of an ion-containing polymer and especially a solventless dispersion of a perfluorosulfonic acid ionomer, and thereafter contacting the dispersion- or solution-wetted substrate with a solution of a salt or of a strongly ionizing acid of a sufficient concentration to cause an adherent coating of the ion-containing polymer to be formed on the substrate.

Abstract: A reverse osmosis membrane having a support which itself has properties of salt rejection laminated to a layer of a cross-linked polyol. The support is a sulphonated aromatic polyether sulphone, and the polyol ma be polyvinyl alcohol.

Abstract: A material, which may have a highly open structure such that it has negligible barrier properties, is treated with expandable particles. These are then caused to expand within the material, reducing its openness and improving its barrier properties. The product may be a porous material. The pores may be modified by an agent applied together with the particles or after the expansion. The particles may be thermoplastic microspheres containing gas. The material may be a network material, with a fiber matrix with many voids.

Abstract: The invention pertains to the polymerization of molecules having electrophilic and nucleophilic substituents on the same or different molecules, such polymerization mediated by aminopyridine catalysts which are substantially regenerated during polymerization. The invention also pertains to polymer products of such polymerization, to permselective membranes containing such polymers, and to processes and apparatus for separating fluids.

Abstract: Polyimide resin dope having at least three fluorine atoms in a repeating molecular unit and an organic solvent (A) are extruded in a tube form or coating the dope on a supporting body. The polyimide resin dope is then immersed in a solvent (B), which the organic solvent (A) is miscible with the solvent (B). Thus, a polyimide-type gas separation membrane including fluorine is virtually defect free in the skin layer, and manufactured cost-effectively by a simple manufacturing method.

Abstract: Composites in the form of a three-dimensional framework or skeleton of ceic particles are formed by a low cost, low temperature sintering process which decomposes a pre-ceramic inorganic or organic precursor. Upon heating, preferably in air, the precursor decomposes to form a ceramic phase in the form of necks between the individual ceramic particles. The properties of the resulting porous ceramic bodies can be modified, such as toughened by impregnation with monomers, oligomers or polymers which are polymerized or cured in situ. Such composites find use as cosmetic products or protheses for humans and animals, such as dental restoratives and bone implants. Methods of fabrication are disclosed which include the use of a pre-ceramic polymer as a binder for the ceramic particles which forms the necks of material between the individual ceramic particles upon firing.

Abstract: This invention relates to methods for preparing membranes of polyfluoroethylene (PTFE) and to the asymmetric membranes fabricated thereby. Such membranes are useful as separation and ultrafiltration membranes. The membranes are produced as a single layer. Method steps including contacting a substrate with a solution of PTFE in a perfluorinated cycloalkane solvent at a high temperature to cause a film of such solution to be coated on the substrate, removing the coated substrate from the solution and rapidly cooling it by contact with a second solvent, removing the coated substrate from the second solvent, drying the film, and optionally separating film from substrate.

Abstract: A reactive membrane for removing impurities, such as water, oxygen and organic compounds, from a gas is provided. The reactive membrane includes a porous inorganic substrate having exposed surfaces and at least one carbon layer, which is modified to present active sites, deposited on the exposed surfaces. The active sites include metal species which are at least partially deoxygenated and are chemically bonded to the carbon layer. Methods of forming the reactive membrane and of removing impurities from a gas with the membrane are also provided.

Abstract: Process for the preparation of an asbestos-free microporous electroconductive substrate. The process includes (a) providing an aqueous suspension of a mixture of carbon or graphite fibers, polytetrafluoroethylene fibers, inert mineral fibers, at least one fluorinated polymer, a silica porogen, and, optionally, at least one thickening agent; (b) depositing a coating onto a porous support by programmedly vacuum filtering said suspension therethrough, the coating comprising a liquid medium; (c) removing the liquid medium from said coating and then drying same; (d) sintering the coating thus formed; and (e) extracting the silica porogen therefrom. A substrate including intimate admixture of carbon or graphite fibers, polytetrafluoroethylene fibers and inert mineral fibers, and optionally, at least one thickening agent, consolidated by a binding amount of at least one fluorinated polymer is formed. The substrate produced is well suited for the electrolysis of solutions of, e.g., alkali metal halides.

Abstract: Inorganic membranes such as zeolite membranes or other molecular sieve membranes can be provided by using siliconee, polymer material as starting material. A thin film zeolite membrane or a thin film membrane formed of interlocking zeolite crystals can be provided. Water soluble or water insoluble silicones can be treated in a basic solution under conditions and with an appropriate structure directing template, suitable aluminum content and at a temperature that is appropriate for growing a desired inorganic crystal framework. Heteroatoms can be included in the crystalline framework.

Abstract: A microminiature combustible gas sensor and a method of fabricating a microminiature combustible gas sensor are provided in which the catalytically active detector comprises a high surface area refractory catalyst support. A microminiature combustible gas sensor is also provided which comprises a catalytically active detector and a diffusion/flow restrictor for limiting the amount of combustion fuel reaching the catalytically active detector. The restrictor causes the catalytic reaction occurring in the vicinity of the catalytically active detector element to become substantially diffusion limited and reduces the power requirements of the sensor. The restrictor also reduces convective heat losses which may arise because of the large temperature gradient surrounding the catalytically active detector element. Finally, a microminiature combustible gas sensor comprising a flashback arrestor with one or more generally linear capillaries for preventing flashback is provided.

Abstract: A method and apparatus for making carbon-encapsulated ultrafine metal particles, in which metal powder intended for encapsulation is injected at a rate up to 25 grams per minutes into a plasma arc so that the metal powder is vaporized. The vaporized metal powder is then mixed with an active gas flow, which consists of hydrocarbons, filled in the surrounding area of the plasma arc, and thereby the vaporized metal powder and the active gas interact continuously producing carbon encapsulated ultrafine metal particles that are remarkably predictable in particle size, distribution of sizes and atomic composition.

Abstract: An oxygen concentration detector includes a one-end closed cylindrical oxygen sensing element having an inside electrode, outside electrode provided on the inner side and outer side respectively, an electrode protecting layer made up of ceramics porous member provided further outside the outside electrode, and a trap layer 1 of ceramics porous member having a surface roughness of 20 to 100 .mu.m measured according to a 10 point mean roughness measurement and provided outside the electrode protecting layer is employed. By dipping the to-be-detected gas side surface of an oxygen sensing element into a slurry with coarse heat-resisting metal oxide particles, 2 to 50 .mu.m in average grain size, dispersed, depositing the slurry on the surface of a protective layer of an oxygen sensor element, thereafter drying and baking the deposit, a porous poisonous substance trap layer, 10 to 500 .mu.m thick, is formed.

Abstract: The invention provides a membrane for separating molecules from mixtures, which membrane consists virtually exclusively of molecular sieve crystals, has a thickness of 0.01-10 mm and has a separating top layer with a thickness of 0.01-10 .mu.m and an effective pore size of less than 1.5 nm, which pore size can be adjusted depending on the molecules to be separated off. The separating membrane can be produced by a method in which: a) pulverulent molecular sieve material and oxides constituting the molecular sieve material, especially zeolite and kaolin and/or silicon dioxide, are mixed, preferably in the presence of water; b) the mixture is shaped; c) the moulding is calcined; d) the calcined moulding is treated with an aqueous solution which promotes crystallization; and e) the moulding is treated with a solution of the oxides constituting the molecular sieve material, and then rinsed and dried. The separating membrane can consist of one component or be combined with, for example, an alumina support.

Abstract: A method of producing a high permeable composite reverse osmosis membrane which comprises forming a polyamide type skin layer on a porous support by the process comprising a step of coating a solution A containing a compound having at least two reactive amino groups on the porous support and a step of contacting a solution B containing a polyfunctional acid halide with the coated layer of the solution A, wherein the difference between a solubility parameter of the solution A and a solubility parameter of the solution B is from 7 to 15 (cal/cm.sup.3).sup.1/2.

Abstract: An improvement process for producing a coated porous ceramic, ceramic composite or metal structure, wherein the impregnation step is carried out by (a) fluidizing said slurry with steam or heated water and spraying said shape with said fluidized slurry or (b) heating said slurry so as to reduce its viscosity and spraying said shape with said reduced viscosity slurry. Manufacture of a single component which functions both as a filter and as a heating element, is made possible by the process of the present invention.

Abstract: A composite porous article is formed from a porous polymeric substrate having its entire surface modified with a cross-linked polymer which results in a hydrophobic and oleophobic surface. The composite retains substantially all of the other original properties of the substrate. The cross-linked polymer is formed in situ on the polymeric substrate from a reactant system comprising an ethylenically unsaturated monomer having at least one fluoroalkyl group, a cross-linker, and, if needed, a polymerization initiator, dissolved in a polar solvent system. The porous substrate saturated with the reactant system is exposed to a suitable energy source to effect polymerization and cross-linking of the monomer.

Abstract: Diaphragm for use in cells for the electrolysis of alkaline halide solutions comprising: 100 parts by weight of asbestos fibers, 30 to 70 parts by weight of silica-based derivatives and 20 to 60 parts by weight of fluorinated polymers, deposited on a porous material. The weight ratio of the fluorinated polymers and the silica-based derivatives is between 0.6 to 1.2 and preferably between 0.6 to 0.9 with the exception of a diaphragm obtained by depositing a suspension comprising 100 parts by dry weight of asbestos fibers, 30 parts by dry weight of silica-based derivatives, 25 parts by dry weight of fluorinated polymers and 1.5 parts by dry weight of a thickening agent. The invention also concerns a method for the preparation of an optionally microporous diaphragm. The diaphragms of the invention are especially useful in aqueous alkaline halide solutions electrolysis cells.

Abstract: Fabrication of the surface-grafted microporous membranes by coating the membrane with an N-halogenated compound, followed by grafting with an unsaturated monomer and sodium dithionite in a primarily aqueous solution that may contain an organic halogen compound selected from carbon tetrachloride and trichloroacetic acid. The coating may be formed in situ and may be cross-linked.

Abstract: A charge mosaic membrane is made of a cationic polymer and an anionic polymer. At least one of the cationic and anionic polymers is in the form of spheres having a diameter of 0.01-10 .mu.m. A process for the production of the charge mosaic membrane is also described.

Abstract: A process for preparing water-based pyrotechnic active compositions containing metal powder is described, which comprises coating the metal powder with a plastic which is insoluble in dilute acids and water and is substantially impermeable to water and oxygen, the coating being present in a quantity of not more than 5 per cent by weight, relative to the total mass of the metal powder, and suspending the powder obtained in water, mixing it with the other constituents of the active composition and bringing it to the desired shape, the coating of the metal powder preferably being carried out by the fluidized-bed process.

Abstract: The process of producing a reverse osmosis membrane by the steps of preparing a liquid mixture of N-vinyl pyrrolidone, maleic anhydride and maleimide, wetting a porous membrane with the mixture and irradiating the wetted membrane with laser energy with energy sufficient to polymerize the mixture to form a terpolymer of N-vinyl pyrrolidone, maleic anhydride and maleimide on the membrane.

Abstract: The reversible thermal recording medium of the invention is composed by forming on a substrate a porous reversible thermal recording layer which reversibly shows transparent states and opaque states by cooling after two modes of heating, by means of organic crystal particles dispersed in matrix polymer. One method for manufacturing a reversible thermal recording medium of the invention includes a coating step for applying a paint in which a matrix polymer, organic crystal particles and pore forming particles are contained and at least one of matrix polymer and organic crystal particles is dispersed in a granular form on a substrate to form a coating layer; plus a solvent contact step of eluting the pore forming particles by causing the coating layer to come into contact with a solvent in which the pore forming particles are soluble; and a drying step.

Abstract: A microporous membrane structure is disclosed that comprises a microporous membrane formed of a synthetic polymer and a substantially continuous porous coating on the membrane. The coating is formed from a urethane-based polymer, and provides a permeable barrier that does not interfere with the function of the membrane, and which will prevent further materials that are applied to or adjacent the membrane from interfering with the function of the membrane when those further materials are applied to the porous coating.

Abstract: A thin fluoropolymer film is covalently bonded to a microporous ptfe film to make a bilayer for separation, filtration or reverse osmosis, by exposing the microporous film to perfluorocyclohexane under plasma.

Abstract: A method of forming inorganic membranes which are highly selective to permeation of hydrogen by temporarily forming a carbon barrier in the pores of a porous substrate, followed by chemical deposition of SiO.sub.2, B.sub.2 O.sub.3, TiO.sub.2, Al.sub.2 O.sub.3 and mixtures thereof in the pores, followed by removal of the carbon barrier. It has been demonstrated that the permeation selective layers thusly formed by this invention have a five fold increase in permeance over such layers made by a similar method but without forming a temporary carbon barrier in the pores of the porous substrate, and removal of the carbon-barrier after establishment of the oxide membrane. Some suitable porous substrate are Vycor.TM. glass or Al.sub.2 O.sub.3.

Abstract: The present invention provides a supported microporous filtration membrane comprising a porous nonwoven fibrous support material having first and second sides, and a continuous microporous membrane having first and second zones, wherein the first side of the support material is integral with the first zone while not protruding into the second zone, and the first zone has a pore size at least about 50% greater than the pore size of the second zone. A method of preparing such a supported microporous membrane is also provided by the present invention.

Abstract: Process and system for protecting an oxidizable material against oxidation.The process according to the invention consists of forming a gas-permeable body (1) having open pores (28), a first surface (2) intended to come into contact with an oxidizing gaseous flow (4) liable to oxidize the body and a second surface (6) opposite to the first surface and injecting an oxygen-free protective gas (8) through the second surface (6) leading to disturbances in the material giving it a protection against oxidation.

Abstract: A process for producing continuous polyurethane suede-type synthetic leather including steps of applying dipping treatment to a fabric with a thickness of 0.2-2.0 mm, pressing the fabric with pressing rollers at a pressure of 0-50 kg, ironing the fabric with ironing wheels at a temperature of 50-150 C./wheel, covering the fabric with a layer of wet coating so that the fabric together with the coating has a thickness of 1.0-2.0 mm, cooling the fabric by a 0-50% DMF solution at a water temperature of 5-40 C., cleansing the fabric at a temperature of 30-100 C., pressing the fabric at a pressure of 0-5 kg, preheating the fabric with one to fifteen preheating wheels at a temperature of 50-200 C., drying the fabric at a temperature of 50-200 C. to obtain a semi-product, and slicing the semi-product into a first sheet of upper polyurethane suede-like synthetic leather and a second sheet of lower polyurethane suede-like synthetic leather with fabric.

Abstract: A hollow fiber membrane ("fiber") comprises a tubular macroporous support coated on its outer surface with a thin tubular asymmetric semipermeable film of polymer. The film, by itself, is non-self-supporting. The support itself is so flexible (flaccid) that it does not have a circular cross-section and collapses with finger pressure. Such a tube of knitted or woven braid no greater than 2.5 mm o.d., having interstitial voids which are non-uniformly shaped by the "ends" which are braided, is coated with a "dope" of polymer, then coagulated in a bath to form the film. Yet, after coating, the braided membrane can withstand up to 1500 psig in hydraulic compression forces before a straight-line relationship between flux and pressure begins to flatten out. The voids are relatively much larger than pores in the film. These voids are small enough to inhibit substantial penetration of the dope which lies superficially supported on the upper portion of the braid.