A radiation-curable composition comprising: a) 10 to 65 wt % of curable ionic compound(s) comprising one ethylenically unsaturated group; b) 3 to 60 wt % of crosslinking agent(s) comprising at least two ethylenically unsaturated groups and having a number average molecular weight below 800; c) 5 to 55 wt % of inert solvent(s) having a boiling point above 100? C.; d) 0 to 10 wt % of free-radical initiator(s); and e) 0.5 to 25 wt % of thickening agent(s).

The present invention deals with a method for obtaining membranes in the form of hollow fibers with application in the field of carbon dioxide removal from natural gas. The aforementioned membranes are obtained by means of heat treatment of polymeric membranes. In this method, polymeric membranes are obtained by a phase-inversion technique by immersion-precipitation and are subsequently subjected to a heat treatment, that is, that the membranes effectively become precursor membranes of the heat treatment. The heat treatment process involves the optimization of the heating rate, temperature, and stabilization time variables, aiming at the improvement of the transport properties of the polymeric membranes. After the heat treatment, it becomes possible to use the membranes in separation processes of gases which operate at pressures greater than 30 bar, with selectivity for carbon dioxide (CO.sub.2).

One aspect of the present invention concerns a porous hollow fiber membrane containing a vinylidene fluoride-based resin. The hollow fiber membrane has a gradient structure in which a pore diameter of pores in the hollow fiber membrane gradually becomes smaller at least toward one of inner and outer peripheral surface sides and is hydrophilized by containing a crosslinked body of a polyvinylpyrrolidone-based resin.

An method of making a porous asymmetric membrane involves dissolving a poly(phenylene ether), poly(phenylene ether) copolymer, polyethersulfone, polysulfone, polyphenylsulfone, polyimide, polyetherimide, polyvinylidene fluoride, or a combination thereof in a water-miscible polar aprotic solvent to provide a membrane-forming composition; and phase-inverting the membrane-forming composition in a first non-solvent composition composed of water, a water-miscible polar aprotic solvent, or a mixture thereof, and a polymer additive dissolved in the first non-solvent composition. The method can be a method of making a hollow fiber by coextrusion through a spinneret having an annulus and a bore, including coextruding the membrane-forming composition through the annulus, and the first non-solvent composition through the bore, into a second non-solvent composition composed of water, a water-miscible polar aprotic solvent, or a mixture thereof to form the hollow fiber.

Asymmetric membranes in hollow fiber and flat sheet forms are disclosed herewith. The process of preparation of the membranes is further disclosed. The membranes are characterized and find application in the separation of gases and solutes.

Membranes having a permselective active layer of a copolymerized perfluorinated monomer and an non-fluorinated alkylvinylester monomer demonstrate superior selective permeability performance for separating gas mixtures compared to membranes of exclusively perfluorinated polymers. Preferred active layer compositions are copolymers of perfluoro-2,2-dimethyl-1,3 dioxole (PDD) copolymerized with an alkylvinyl ester such as vinyl acetate, and vinyl pivalate, and with alkylvinyl esters that are substantially hydrolyzed to provide copolymerized vinyl alcohol functionality. The membranes can have a thin, high diffusion rate, gutter layer of a fluorinated polymer highly permeable to nitrogen positioned between the active layer and a porous support layer. A novel copolymer effective in selectively permeable membranes is a copolymer of PDD and an alkylvinyl ester compound having the formula H.sub.2C?CHOC(0)R.sup.1 in which R.sup.1 is a linear or branched alkyl group of from 2 to 5 carbon atoms.

Provided are a ceramic separation membrane structure improved in separation performance with no reduction in permeability, and a method for producing the structure. The ceramic separation membrane structure includes a ceramic porous body, a zeolite separation membrane disposed on the ceramic porous body, and a repair portion made of a repairing material of organic-inorganic hybrid silica. The organic-inorganic hybrid silica is a combination of an organic component and a silicon-containing inorganic component.

The invention relates to a porous separation article having a fluoropolymer, polyamide, PEEK, or PEKK binder interconnecting one or more types of interactive powdery materials or fibers. The interconnectivity is such that the binder connects the powdery materials or fibers in discrete spots rather than as a complete coating, allowing the materials or fibers to be in direct contact with, and interact with a fluid. The resulting article is a formed multicomponent, interconnected web, with porosity. The separation article is useful in water purification, as well as in the separation of dissolved or suspended materials in both aqueous and non-aqueous systems in industrial uses. The separation article can function at ambient temperature, as well as at elevated temperatures.

The present invention is directed to methods of treating a hydrocarbon-containing waste stream to form a hydrocarbon-containing retentate and an aqueous permeate which is substantially free of hydrocarbon. The method includes passing the hydrocarbon-containing waste stream through a microporous membrane to yield the hydrocarbon-containing retentate and the aqueous permeate. The membrane comprises a substantially hydrophobic, polymeric matrix and substantially hydrophilic, finely divided, particulate filler distributed throughout the matrix. The polymeric matrix has pores with a volume average diameter less than 1.0 micron, and at least 50 percent of the pores have a mean diameter of less than 0.35 micron.

Disclosed are a bundle of hollow fiber membranes to improve use efficiency of the hollow fiber membranes and a method of manufacturing the same. The bundle of hollow fiber membranes includes a plurality of yarns to form fluid channels and serve as spacers disposed between the hollow fiber membranes to create a bundle. The method includes spinning including supplying a spinning dope to a nozzle and conducting spinning to form a plurality of hollow fiber membranes, coagulating the hollow fiber membranes formed during spinning, and yarn feeding including inserting a plurality of yarns between the hollow fiber membranes to form a bundle. The method is effective in uniformly distributing a fluid through fluid channels formed between the hollow fiber membranes and maximizes usage efficiency of the hollow fiber membranes.