Cyclic Patents (Class 210/500.28)
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Patent number: 7665615Abstract: A composite article includes a base material and a porous membrane laminated with the base material. The porous membrane has hydrophobic properties and includes at least one of expanded polytetrafluoroethylene, woven polytetrafluoroethylene, and non woven polytetrafluoroethylene. A coating layer is formed on at least a portion of the porous membrane. The coating layer has hydrophilic properties and includes at least one of an organofunctional siloxane and a polyether urethane polymer.Type: GrantFiled: September 30, 2005Date of Patent: February 23, 2010Assignee: General Electric CompanyInventors: Karmin Lorraine Olson, Alan Smithies
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Patent number: 7662212Abstract: The invention relates to polymeric ultrafiltration or microfiltration membranes of, for instance, Halar, PVDF or PP, incorporating PVME or vinyl methyl ether monomers. The PVME may be present as a coating on the membrane or dispersed throughout the membrane or both. The membranes are preferably hydrophilic with a highly asymmetric structure with a reduced pore size and/or absence of macrovoids as a result of the addition of PVME. The PVME maybe cross-linked. The invention also relates to methods of hydrophilising membranes and/or preparing hydrophilic membranes via thermal or diffusion induced phase separation processed.Type: GrantFiled: July 8, 2004Date of Patent: February 16, 2010Assignee: Siemens Water Technologies Corp.Inventors: Daniel Mullette, Joachim Muller, Neeta Patel
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Publication number: 20100006495Abstract: A polyamide membrane comprising reaction product of an anhydrous solution comprising an anhydrous solvent, at least one polyfunctional secondary amine and a pre-polymer deposition catalyst; and an anhydrous, organic solvent solution comprising a polyfunctional aromatic amine-reactive reactant comprising one ring. A composite semipermeable membrane comprising the polyamide membrane on a porous support. A method of making a composite semipermeable membrane by coating a porous support with an anhydrous solution comprising an anhydrous solvent, a polyfunctional secondary amine and a pre-polymer deposition catalyst, to form an activated pre-polymer layer on the porous support and contacting the activated pre-polymer layer with an anhydrous, organic solvent solution comprising a polyfunctional amine-reactive reactant to interfacially condense the amine-reactive reactant with the polyfunctional secondary amine, thereby forming a cross-linked, interfacial polyamide layer on the porous support.Type: ApplicationFiled: July 9, 2008Publication date: January 14, 2010Applicant: ELTRON RESEARCH AND DEVELOPMENT, INC.Inventor: Wayne E. BUSCHMANN
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Publication number: 20100006496Abstract: Provided is a water separation membrane capable of effectively separating water from a water solution of ethanol, saccharide or the like. The water separation membrane is composed of polypyrrole doped with a sulfonate ion. The sulfonate ion may be an aromatic or aliphatic sulfonate ion.Type: ApplicationFiled: July 14, 2009Publication date: January 14, 2010Applicant: Honda Motor Co., Ltd.Inventors: Akihisa Tanaka, Kazuhiro Kagawa, Pu Qian
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Publication number: 20090277837Abstract: The present invention discloses fluoropolymer coated membranes and methods for making and using these membranes. The fluoropolymer coated membranes described in the current invention are prepared by coating a porous asymmetric membrane layer with a thin layer of fluoropolymer coating. The porous asymmetric membrane layer comprises an asymmetric cellulosic membrane, an asymmetric polymer membrane, or an asymmetric molecular sieve/polymer mixed matrix membrane with a low selectivity and high permeance. The fluoropolymer coating improves the selectivity of the porous asymmetric membrane layer and maintains the membrane performance with time.Type: ApplicationFiled: May 6, 2008Publication date: November 12, 2009Inventors: Chunqing Liu, Man-Wing Tang
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Patent number: 7572321Abstract: A membrane 12 that exhibits superior condensation resistance regardless of the type of moisture-permeable resin, that has satisfactory adhesion between a porous film and a reinforcing member, and that can be manufactured in a simple manner. The membrane 12 is a laminated article 23 containing a porous film 20 and a reinforcing member 40, and the reinforcing member 40 has a moisture-permeable resin layer 30 on the side of an interface 50 with the porous film 20. To reliably form the moisture-permeable resin layer (moisture-permeable resin film) 30, the average pore diameter of the porous film 20 is preferably 0.01 to 10 ?m, and the porosity of the reinforcing member 40 is preferably 30 to 95%. According to the membrane 12 of the present invention, even if the moisture-permeable resin is water-soluble (for example, polyvinyl alcohol), condensation resistance is still satisfactory.Type: GrantFiled: November 1, 2005Date of Patent: August 11, 2009Assignee: Japan Gore-Tex, Inc.Inventors: Keiichi Yamakawa, Takashi Imai
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Publication number: 20090184047Abstract: Functionalized nanopore membranes, apparatus and related methods, as can be used for selective analyte detection and/or separation.Type: ApplicationFiled: January 14, 2009Publication date: July 23, 2009Inventors: Sankaran Thayumanavan, Kothandam Krishnamoorthy, Elamprakash N. Savariar
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Patent number: 7556677Abstract: There is provided an asymmetric integrally skinned membrane comprising a polyimide and another polymer selected from the group consisting of polyvinylpyrrolidone, sulfonated polyetheretherketones and mixtures thereof. The membrane which is substantially insoluble in an organic solvent and substantially defect-free can be useful as a separation membrane.Type: GrantFiled: January 17, 2006Date of Patent: July 7, 2009Assignee: Vaperma Inc.Inventors: Richard Cranford, Christian Roy
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Patent number: 7553417Abstract: Functionalized substrates, methods of making functionalized substrates, and methods of using functionalized substrates are disclosed.Type: GrantFiled: December 15, 2006Date of Patent: June 30, 2009Assignee: 3M Innovative Properties CompanyInventors: Clinton P. Waller, Jr., Douglas Eugene Weiss
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Publication number: 20090092624Abstract: The present invention relates in part to antiinfective flavononol compounds represented by formula I: Another aspect of the invention is a method for treating an infection in a subject by administering the compounds of Formula I to the subject.Type: ApplicationFiled: August 15, 2008Publication date: April 9, 2009Inventors: Randall S. Alberte, William P. Roschek, JR.
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Publication number: 20090071903Abstract: There is provided a composite semipermeable membrane that shows a high salt removal ratio and high performance in rejecting boron that is not dissociated in the neutral region. The composite semipermeable membrane is produced by a process that includes forming a separating functional polyamide layer on a porous substrate film, while using an organic solvent solution containing a specific cyclic aliphatic compound or a specific aromatic compound such that a polyamide molecule that forms the separating functional polyamide layer has a partial structure composed of “a cyclic aliphatic group or an aromatic group having at least two specific substituents, at least one of which contains a heteroatom bond and a carbonyl group at the ? or ? position”.Type: ApplicationFiled: December 13, 2006Publication date: March 19, 2009Applicant: TORAY INDUSTRIES, INC.Inventors: Koji Nakatsuji, Hiroki Tomioka
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Patent number: 7462223Abstract: The present invention relates to a polymer blend membrane comprising a bridged polymer which is produced by a selected process. The membrane of the invention displays a significantly improved fracture toughness (elongation at break/stress) combined with virtually unchanged other properties. The membranes of the invention are suitable for producing membrane-electrode units for fuel cells.Type: GrantFiled: August 10, 2002Date of Patent: December 9, 2008Assignee: BASF Fuel Cell GmbHInventors: Joachim Kiefer, Oemer Uensal
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Publication number: 20080296225Abstract: Water permeable membranes and methods of forming water permeable membranes are provided. The water permeable membranes are comprised of a cross-linked polyamide containing at least one bifunctional additive that is hydrophilic and reactive. Additionally, in accordance with other embodiments of this invention, methods of forming water permeable membranes comprised of a cross-linked polyamide containing at least one bifunctional additive that is hydrophilic and reactive are provided. Specifically, the water permeable membranes may comprise a membrane formed from a cross-linked aromatic or aromatic/aliphatic polyamide interfacially polymerized on a porous support. The presence of the at least one hydrophilic and reactive additive improves the flux and salt retention properties of the membrane in comparison to a membrane formed without the at least one hydrophilic and reactive additive.Type: ApplicationFiled: July 17, 2008Publication date: December 4, 2008Inventor: W.S. Winston Ho
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Patent number: 7438193Abstract: Provided are a nanoporous membrane and a method of fabricating the same. The nanoporous membrane includes a support, and a separation layer including a plurality of nano-sized pores at a density of 1010/cm2 or greater and a matrix. The nanoporous membrane has a high flux and a high selectivity.Type: GrantFiled: April 14, 2006Date of Patent: October 21, 2008Assignees: Postech Foundation, Postech Academy-Industry FoundationInventors: Seung Yun Yang, Jin Kon Kim, Min Soo Park, Incheol Ryu, Sung Key Jang, Hwang Yong Kim, Thomas P. Russell
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Publication number: 20080149561Abstract: Articles comprising a fibrous support of nanofibers and an interfacially polymerized polymer layer disposed on a surface of the fibrous support are useful, e.g., as fluid separation membranes.Type: ApplicationFiled: December 5, 2007Publication date: June 26, 2008Inventors: Benjamin Chu, Benjamin Hsiao, Kyunghwan Yoon
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Publication number: 20080135481Abstract: A method for hemodialysis and hemofiltration includes contacting blood with a porous membrane in a hollow fiber or flat sheet configuration. The membrane comprises a polyarylethernitrile sulfone having structural units of formula I wherein R1 and R2 are independently H, nitro, a C1-C12 aliphatic radical, a C3-C12 aromatic radical, or a combination thereof; a is 0, 1, 2 or 3; b is 0, 1, 2, 3 or 4; and m and n are independently 0 or 1.Type: ApplicationFiled: December 6, 2006Publication date: June 12, 2008Applicant: GENERAL ELECTRIC COMPANYInventors: Daniel Steiger, Yanshi Zhang, Gary William Yeager
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Publication number: 20080035566Abstract: This invention relates to a polymer membrane assembly for selective separation of permeate compositions by carbon weight. This invention also relates to a process for utilizing these polymer membrane assemblies in separation processes for selective carbon weight separation of hydrocarbon feedstreams components. More particularly, but not by way of limitation, this invention relates to the use membrane assemblies for the selective separation by carbon weight of aromatics from a hydrocarbon based feedstream.Type: ApplicationFiled: August 3, 2007Publication date: February 14, 2008Inventors: Craig Y. Sabottke, Bal K. Kaul, Dennis G. Peiffer
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Publication number: 20080035567Abstract: The present invention includes a polymeric membrane assembly and method for selective separation of components of a feedstream utilizing the polymeric membrane assembly. The present invention is a novel concept for the manufacture and use of a polymeric membrane assemblies which require the use of fibrous backing materials for fabrication processes utilizing commercial membrane casting equipment. This invention involves as improved membrane assembly configuration and membrane separation process configuration resulting in improved flux and selectivity properties for a given polymeric membrane composition.Type: ApplicationFiled: August 3, 2007Publication date: February 14, 2008Inventor: Craig Y. Sabottke
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Patent number: 7229553Abstract: Method for producing a membrane made of bridged polymer and a fuel cell. The present invention relates to a membrane comprising a bridged polymer which is produced by a selected process. The membrane of the invention displays a significantly improved fracture toughness (elongation at break/tensile strength) with virtually unchanged swelling behavior. The membranes of the invention are suitable for producing membrane-electrode units for fuel cells.Type: GrantFiled: March 1, 2002Date of Patent: June 12, 2007Assignee: PEMEAS GmbHInventors: Oemer Uensal, Joachim Kiefer
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Patent number: 7160356Abstract: A polymeric composite may be used for forming fluid separation membranes. The membranes may be formed from polyimide, polyamide or poly (pyrrolone-imide) materials. Polyamides may be formed by the condensation of a tetraamine, a tetraacid, and a diamine. Polyimides and poly (pyrrolone-imides) may be formed by the cyclization of a polymer precursor. A polymeric composite may include a dithiolene or a mixture of dithiolenes. A polymer matrix incorporating dithiolenes may exhibit an olefin/paraffin solubility selectivity. A solubility selectivity may be between about 1.1 and about 2.0.Type: GrantFiled: April 15, 2004Date of Patent: January 9, 2007Assignee: Board of Regents, The University of Texas SystemInventors: William J. Koros, Ryan L. Burns
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Patent number: 7074256Abstract: A polyphosphazene having a glass transition temperature (“Tg”) of approximately ?20° C. or less. The polyphosphazene has at least one pendant group attached to a backbone of the polyphosphazene, wherein the pendant group has no halogen atoms. In addition, no aromatic groups are attached to an oxygen atom that is bound to a phosphorus atom of the backbone. The polyphosphazene may have a Tg ranging from approximately ?100° C. to approximately ?20° C. The polyphosphazene may be selected from the group consisting of poly[bis-3-phenyl-1-propoxy)phosphazene], poly[bis-(2-phenyl-1-ethoxy)phosphazene], poly[bis-(dodecanoxypolyethoxy)-phosphazene], and poly[bis-(2-(2-(2-?-undecylenyloxyethoxy)ethoxy)ethoxy)phosphazene]. The polyphosphazene may be used in a separation membrane to selectively separate individual gases from a gas mixture, such as to separate polar gases from nonpolar gases in the gas mixture.Type: GrantFiled: May 13, 2004Date of Patent: July 11, 2006Assignee: Battelle Energy Alliance, LLCInventors: Frederick F. Stewart, Mason K. Harrup, Christopher J. Orme, Thomas A. Luther
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Patent number: 6994788Abstract: A sulfonated aromatic polymer comprising the repeating structural unit of the formula I —O—Ar1(SO3R)n—C(CF3)2—Ar1(SO3R)n—O—Ar2—(X—Ar2)m—, ??(I) in which Ar1 and Ar2 are, independently of one another, divalent aromatic or heteroaromatic radicals which are optionally substituted by one or more monovalent organic groups which are inert under the conditions of use, R is hydrogen, an alkali metal or alkaline earth metal ion or an ammonium ion, n is an integer from 0 to 3, m is 0, 1 or 2 and X is a —CO—, —O—, —CpH2p—, —CpF2p— or —S— group, in which p is an integer from 1 to 10, is described. Membranes with high proton conductivities can be produced from this polymer and are preferably used in fuel cells.Type: GrantFiled: March 1, 2000Date of Patent: February 7, 2006Assignee: PEMEAS GmbHInventors: Alexander Dyck, Thomas Soczka-Guth
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Patent number: 6986844Abstract: Solvent-resistant polybenzimidazole membranes, methods of making them and crosslinking them and composite membranes and hollow fiber membrane modules from them are disclosed.Type: GrantFiled: June 27, 2003Date of Patent: January 17, 2006Assignee: Bend Research, Inc.Inventors: Robert P. Barss, Dwayne T. Friesen, Scott B. McCray, Kendall R. Pearson, Roderick J. Ray, Delores R. Sidwell, James B. West
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Patent number: 6841068Abstract: A domestic nanofiltration membrane based water purifier without a storage tank. The water purifier according to the present invention uses a nanofiltration membrane filter as a main filtering section and does not have a storage tank for containment of purified water. Although conventional reverse osmosis membrane based water purification systems provide good quality water, they have problems in that installation of the storage tanks due to insufficient flow rate results in the increased volumes of water purifiers, and at the same time, secondary pollution may be caused by microorganism propagation upon prolonged storage. In this regard, the present invention provides a domestic nanofiltration membrane based water purifier without a storage tank, in which a nanofiltration membrane filter with a pore size of approximately 0.1 to 10 nm is used as a main filtering section.Type: GrantFiled: January 13, 2003Date of Patent: January 11, 2005Assignee: Saehan Industries IncorporationInventors: Sung Ro Yoon, Soon Sik Kim, Hoon Hyung, Young Hoon Kim
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Patent number: 6814865Abstract: The invention includes novel anion exchange membranes formed by in situ polymerization of at least one monomer, polymer or copolymer on a woven support membrane and their methods of formation. The woven support membrane is preferably a woven PVC membrane. The invention also includes novel cation exchange membranes with or without woven support membranes and their methods of formation. The invention encompasses a process for using the membranes in electrodialysis of ionic solutions and in particular industrial effluents or brackish water or seawater. The electrodialysis process need not include a step to remove excess ions prior to electrodialysis and produces less waste by-product and/or by-products which can be recycled.Type: GrantFiled: December 5, 2001Date of Patent: November 9, 2004Assignee: Seventy-Seventh Meridian Corporation LLCInventors: Tejraj Aminabhavi, Padmakar V. Kulkarni, Mahadevappa Y. Kariduraganavar
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Patent number: 6746595Abstract: An ammonium selective ionophore for use in ion selective electrodes.Type: GrantFiled: January 7, 2002Date of Patent: June 8, 2004Assignees: Bayer Corporation, Worcester Polytechnic InstituteInventors: John S. Benco, W. Grant McGimpsey
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Patent number: 6726840Abstract: Porous membranes of (per)fluorinated amorphous polymers having a porosity in the range 5-500 nm, preferably 20-100 nm, measured by an atomic force electronic microscope; the membrane pore average size distribution being narrow, about 80%-90% of the pores have a size ranging from minus 5 nm to plus 5 nm of the value of the distribution maximum peak.Type: GrantFiled: May 24, 2000Date of Patent: April 27, 2004Assignee: Ausimont S.p.A.Inventors: Vincenzo Arcella, Amalia Gordano, Patrizia Maccone, Enrico Drioli
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Patent number: 6649058Abstract: The invention relates to a hollow membrane (11) comprising two support layers arranged one above the other forming a space between them and a plurality of capillary tubes arranged between the support layers forming capillary channels for the flow of a first fluid, the space between the capillary tubes forming an internal cavity for the circulation of a second fluid around the capillary tubes, and the whole assembly being made of an organic polymer. These membranes (11) can be assembled into modules for the treatment of a fluid with intermediate porous panels (13).Type: GrantFiled: March 19, 2001Date of Patent: November 18, 2003Assignees: Commissariat a l'Energie AtomiqueInventors: Nicolaï Jitariouk, Alain Le Moel
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Patent number: 6558546Abstract: A pore plugging material, for pH dependent membrane diffusion, in which cyclic olefins having phosphazene-functional moieties provide predictable erosion properties when used to plug pores in separation barriers and other porous membranes. Specific properties of the polymers are dependent on several factors, including molecular weight and identity of side groups attached to the phosphazene moiety. However, as a class, phosphazene-functional cyclic olefins provide both predictable erodibility and uniformly benign hydrolysis products and are, therefore, uniquely suitable as pore plugging polymers for separation barriers and membranes of all kinds. The invention, therefore, embraces the provision of a pH-sensitive erodible pore plugging material for pores in separation barriers and membranes of all kinds.Type: GrantFiled: November 1, 2001Date of Patent: May 6, 2003Assignee: The Penn State Research FoundationInventors: Harry R. Allcock, Jared Bender, Roy H. Hammerstedt, Stephen Schwartz, Walter Laredo
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Patent number: 6540915Abstract: Cast semi-permeable membranes made from synthetic polymer used in reverse osmosis, ultrafiltration and microfiltration are treated with a non-leaching antimicrobial agent to prevent its bio-fouling and bacterial breakthrough. The semi-permeable membranes include a polymeric material and a non-leaching antimicrobial agent that is incorporated into and homogeneously distributed throughout the polymeric material. The polymeric material, in the case of one membrane, may be cellulose acetate. In the case of thin film composite polyamide membranes, the antimicrobial agent is incorporated in a microporous polysulfone layer that is sandwiched between a reinforcing fabric and an ultrathin polyamide material. The invention also includes a treatment of flat and hollow fiber semipermeable membranes made with polysulfones and polyvinylidene fluoride.Type: GrantFiled: May 2, 2001Date of Patent: April 1, 2003Assignee: Microban Products CompanyInventor: Arvind S. Patil
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Publication number: 20030052056Abstract: The present invention relates to polymer membranes for separating olefins from paraffins which have the similar molecular size and close boiling point. More particularly, it relates to a silver salt-containing facilitated transport membrane for olefin separation, and also a method for producing the same. An object of the present invention is to provide a silver salt-containing facilitated transport membrane for olefin separation having improved stability, and also a method for preparing the same, which exhibits no deterioration in membrane performance even when operated for an extended period of time.Type: ApplicationFiled: July 15, 2002Publication date: March 20, 2003Applicant: KOREA INSTITUE OF SCIENCE AND TECHNOLOGYInventors: Hoon Sik Kim, Yong Soo Kang, Byung Gwon Lee, Hyun Joo Lee, Jae Hee Ryu
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Patent number: 6521130Abstract: When forming a separating functional layer containing crosslinked polyamide, by carrying this out in the presence of 1) carboxylic acid ester with a total of 8 or more carbons, or 2) carboxylic acid, it is possible to provide a composite semipermeable membrane which, while still maintaining a high rejection rate, is more outstanding in its water permeability than hitherto.Type: GrantFiled: May 25, 2001Date of Patent: February 18, 2003Assignee: Toray Industries, Inc.Inventors: Shunji Kono, Akihiko Ito, Yoshinari Fusaoka
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Patent number: 6508921Abstract: A lithium ion-selective membrane that favors the bonding of lithium and depresses sodium interference is invented by a charge balance approach. A lithium ion-selective electrode (Li-ISE) having the membrane of this invention demonstrates a fast kinetic response, good precision and reproducibility, high sensitivity and the ability to retain the sensitivity after a long-term contact with biological samples. The sensor shows Nernst linearity with a slope of 55.4 mV for lithium ion concentrations between 0.5 &mgr;mol/L and 10 mmol/L. The membrane includes at least about 2% by weight of 6,6-dibenzyl-1,4,8,11 tetraoxacyclotetradecane ionophore; from about 0.025% to about 1% by weight of potassium tetrakis(4-chlorophenyl)borate additive; a plasticizer; and a polymeric material.Type: GrantFiled: March 24, 2000Date of Patent: January 21, 2003Assignee: Beckman Coulter, Inc.Inventors: Xihai Mu, Chandra P. Jain
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Publication number: 20020088748Abstract: A pore plugging material, for pH dependent membrane diffusion, in which cyclic olefins having phosphazene-functional moieties provide predictable erosion properties when used to plug pores is separation barriers and other porous membranes. Specific properties of the polymers are dependent on several factors, including molecular weight and identity of side groups attached to the phosphazene moiety. However, as a class, phosphazene-functional cyclic olefins provide both predictable erodibility and uniformly benign hydrolysis products and are, therefore, uniquely suitable as pore plugging polymers for separation barriers and membranes of all kinds. The invention, therefore, embraces the provision of a pH-sensitive erodible pore plugging material to pores in separation barriers and membranes of all kinds.Type: ApplicationFiled: November 1, 2001Publication date: July 11, 2002Inventors: Harry R. Allcock, Jared Bender, Roy H. Hammerstedt, Stephen Schwartz, Walter Laredo
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Patent number: 6316684Abstract: A membrane and membrane separation process useful in gas, vapor and liquid separations. The membrane comprises a separating layer of a polymer that is characterized by a high glass transition temperature, Tg, such as at least about 100° C., and a high free volume within the polymer material itself, such as a fractional free volume of at least about 0.20. Within the polymer material are dispersed fine non-porous particles, such as silica or carbon black particles, having an average diameter no greater than about 1,000 Å. The membrane is particularly useful for separating C3+ hydrocarbons from other gases.Type: GrantFiled: September 1, 1999Date of Patent: November 13, 2001Assignee: Membrane Technology and Research, Inc.Inventors: Ingo Pinnau, Zhenjie He
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Publication number: 20010015334Abstract: The present invention relates to a non-volatile facilitated transport separation membrane prepared by using a solid state polymer electrolyte, characterized in that it has good stability and improved permeance and selectivity of alkene-series unsaturated hydrocarbons.Type: ApplicationFiled: December 29, 2000Publication date: August 23, 2001Applicant: Korea Institute of Science and TechnologyInventors: Young-Soo Kang, Hyun-Chae Park, Jong-Ok Won, Seoung-Uk Hong, Tak-Min Kwon
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Patent number: 6258271Abstract: The invention relates to a hollow membrane (11) comprising two support layers arranged one above the other forming a space between them and a plurality of capillary tubes arranged between the support layers forming capillary channels for the flow of a first fluid, the space between the capillary tubes forming an internal cavity for the circulation of a second fluid around the capillary tubes, and the whole assembly being made of an organic polymer. These membranes (11) can be assembled into modules for the treatment of a fluid with intermediate porous panels (13).Type: GrantFiled: August 16, 1999Date of Patent: July 10, 2001Assignee: Commissariat a l'Energie AtomiqueInventors: Nikolaï Jitariouk, Alain le Moel
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Publication number: 20010004976Abstract: The present invention relates to a dialyzer for blood treatment having incorporated therein a semipermeable membrane which comprises a hydrophobic polymer and a hydrophilic polymer, the water permeating performance of the semipermeable membrane after drying being ½ or higher relative to that before drying and the dialyzer satisfying any of the following requirements: (A) the vitamin B12 clearance is not smaller than 135 ml/min per 1.6 m2; and (B) the amount of the hydrophilic polymer that is eluted from the semipermeable membrane is not higher than 10 ppm.Type: ApplicationFiled: December 15, 2000Publication date: June 28, 2001Inventors: Hidetoshi Kozawa, Hidekazu Nakashima, Shigehisa Wada