Abstract: A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Abstract: A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Abstract: A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Abstract: A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Abstract: The invention relates to a terpolymer of tetrafluoroethylene (TFE) monomer, polyvinylidene fluoride (PVDF) monomer and hexafluoropropylene (HFP) monomer for forming an ultrafiltration or microfiltration membrane, method of forming said membranes, and to the ultrafiltration or microfiltration membranes themselves. The invention also relates to a method of forming a polymeric ultrafiltration or microfiltration membrane including preparing a leachant resistant membrane dope which incorporates a leachable pore forming agent, casting a membrane from the dope and leaching the pore forming agent from the membrane. The invention also relates to a method of preparing a polymeric ultrafiltration or microfiltration membrane of improved structure including the step of adding a nucleating agent to the membrane dope before casting.

Abstract: A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Abstract: A process and a device for producing filtration-active fibers is described. An aqueous suspension is produced from a homopolymer of polyacrylonitrile, polyamide or cellulose acetate and the suspension is heated in a tank to a temperature T which is at least 60° above the boiling point of the water and at least 30° C. below the softening temperature of the polymer. The at least plasticized polymer mass which has been obtained in this way is discharged through at least one nozzle means at least using the autogenous pressure of superheated water. The device calls for that the suspension is prepared in a storage tank, that a mixing tank is connected to the storage tank and is made for heating an aqueous polymer suspension under pressure, and that furthermore there is a nozzle means for discharge of the plasticized polymer mass located at the output of the mixing tank.

Abstract: The disclosure is a more economical process for producing fibrets of superior quality by directing a dope comprising a cellulose derivative and a suitable solvent therefor into a coagulant and exposing it there to a shearing field to coagulate of the dope and form the fibrets. The fibrets, the solvent and the coagulant are then separated off. The suspension formed from the dope and the coagulant is alternately accelerated and decelerated in the shearing field at least once, preferably at least twice. This makes it possible to maintain a high average degree of turbulence over a long distance, so that a dope of high viscosity can be processed. In the apparatus for producing fibrets, the at least one nozzle (46-49) is disposed within a dispersing facility (40) comprising rotor (44) and stator (43, 45) and further comprising at least two sprockets (50-53), of which at least one sprocket (50) is part of the rotor (44) of the dispersing facility (40).

Abstract: A multi-layer microfiltration membrane having an integrated prefiltration layer. Pursuant to a phase inversion process, several layers are successively poured out onto one another prior to phase separation of a lower layer, with the viscosity for the pour solution decreasing toward the upper layers. This produces a microporous, multi-layer, integral filtration membrane having a homogenous symmetrical pore structure for the final filtration layer and an open-pored structure for the prefiltration layer disposed therebelow. Even with small pore diameters, this membrane can be easily pleated for installation in filter cartridges without the formation of damage at the crease edges. High throughput rates are possible at a low tendency to clog.

Abstract: A permanently hydrophilic membrane on an aromatic polysulphone basis and a method for its production. Due to their chemical and thermal resistivity and also because they are unobjectionable with respect to their contacting foodstuffs, membranes on an aromatic polysulphone basis represent a preferred filtration material. But since they are hydrophobic, they would have to be hydrophilated before they are used. Known hydrophilation methods were insufficient to maintain the hydrophilic properties of the membranes, especially after repeated sterilization. The new method aims at making the membranes permanently hydrophilic under sterilization conditions. In an aftertreatment step, the membranes on an aromatic polysulphone basis are conducted, before or after drying, through an impregnating bath of polyvinylpyrrolidone, a copolymer of vinylpyrrolidone and one or more hydrophobic monomers and peroxodisulphate, then heated to 70 to 150.degree. C. and cooled down again.

Abstract: Membranes are based on a homogeneous mixture of polyvinylidene fluoride and a second polymer which can be rendered hydrophilic by chemical reaction. The membranes contain 70 to 98 percent by weight of polyvinylidene fluoride and 2 to 30 percent by weight of a polymer formed essentially from polymethyl and/or polyethyl acrylate, and have a maximum pore size in the range from 0.005 to 10 .mu.m. They can be rendered hydrophilic by means of at least partial hydrolysis, at least partial transesterification with an alcohol which is at least trihydric and contains 3 to 12 carbon atoms, and/or at least partial aminolysis with an amino compound having 2 to 8 carbon atoms. The flat or capillary membranes which have been rendered hydrophilic can contain on their total surface 0.001 to 10 milliequivalents/g of membrane, preferably 0.01 to 5 m equivalents/g of membrane, of --COOH, --OH or --NH.sub.2 groups or corresponding mixtures of these hydrophilic functional groups.

Abstract: A process produces microporous powders or shaped articles, in particular membranes in the form of flat films, tubular films or hollow fibers, which may be used for controlled release of an active compound, for dialysis, gas separation, ultrafiltration or microfiltration, from polyvinylidene fluoride and/or polyphenylene sulfide and/or polysulfone and/or polyacrylonitrile and/or ethylene/vinyl alcohol copolymer and/or ethylene/chlorotrifluoroethylene copolymer and/or polyethersulfone and/or polyether-imide and/or polymethyl methacrylate and/or polycarbonate and/or cellulose triacetate. The process utilizes phase separation by means of thermally induced triggering or triggering induced by a non-solvent of a solution of the polymer in a mixture containing .epsilon.-caprolactam as the essential dissolving constituent. The solution may be formed before the phase separation is triggered.

Abstract: A method and catalyst for the determination of nitrate in water which has been obtained by reduction of a solution of a salt of a transition metal or group VIII of the periodic system and a transition metal salt of the copper group in the presence of an acid. The nitrate determination is effected by determining the nitrate extinction of a sample of water as compared with a blank sample in the UV region at 210 nm, a part of the sample of water whose nitrate has been reduced in the presence of hydrogen with the use of the catalyst of the invention being employed as blank sample.