Patents Represented by Attorney George F. Helfrich
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Patent number: 5741883Abstract: Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.Type: GrantFiled: December 16, 1994Date of Patent: April 21, 1998Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventor: Robert G. Bryant
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Patent number: 5694807Abstract: A method and apparatus for determining the mass density of a moving filament is provided. The method includes the steps of providing a filament across two supports, tensioning the filament, inducing a vibration into the filament segment between the supports, reinforcing the vibration using an amplified feedback signal, detecting the vibrational frequency data, processing the data using a fast-fourier transform analysis, and then displaying the frequency. The use of the feedback signal results in a self-tuning resonant loop. Open loop versions may also be used. The apparatus includes a base supporting a fixed support and a transducer which in turn supports a moveable support. The transducer vibrates the moveable support transversely to the direction of travel of the filament, thereby inducing a transverse vibrational mode. The output of the transducer is amplified and used to drive a second amplifier to produce a self-tuning resonant loop.Type: GrantFiled: September 29, 1994Date of Patent: December 9, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Jeffrey A. Hinkley, Joseph M. Marchello
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Patent number: 5689004Abstract: Controlled molecular weight imide oligomers and co-oligomers containing pendent phenylethynyl groups (PEPIs) and endcapped with nonreactive or phenylethynyl groups have been prepared by the cyclodehydration of the precursor amide acid oligomers or co-oligomers containing pendent phenylethynyl groups and endcapped with nonreactive or phenylethynyl groups. The amine terminated amide acid oligomers or co-oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and diamine containing pendent phenylethynyl groups and subsequently endcapped with a phenylethynyl phthalic anhydride or monofunctional anhydride. The anhydride terminated amide acid oligomers and co-oligomers are prepared from the reaction of diamine(s) and diamine containing pendent phenylethynyl group(s) with an excess of dianhydride(s) and subsequently endcapped with a phenylethynyl amine or monofunctional amine.Type: GrantFiled: November 12, 1996Date of Patent: November 18, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: John W. Connell, Joseph G. Smith, Jr., Paul M. Hergenrother
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Patent number: 5681967Abstract: Controlled molecular weight phenylethynyl terminated imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with phenylethynyl phthalic anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydride(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine.Type: GrantFiled: October 21, 1996Date of Patent: October 28, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Paul M. Hergenrother, Joseph G. Smith, Jr.
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Patent number: 5677418Abstract: A silver organic complex, such as silver acetate, is solubilized in a polyamic acid resin or soluble polyimide solution using a suitable solvent such as hexafluoroacetyl acetone. The mixture is stable and can be applied to both flat and contoured surfaces. Application can be performed by casting, dip-coating, spraying, or other suitable techniques. In addition, the mixture can be cast or extruded as a polyimide film which is not applied to an underlying substrate. Upon curing, a flexible silver coated polyimide film is produced.Type: GrantFiled: June 14, 1995Date of Patent: October 14, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: David W. Thompson, Maggie L. Caplan, Anne K. St. Clair
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Patent number: 5670256Abstract: A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3,4'-ODA and ODPA, and endcapped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340.degree. C. to 360.degree. C. and at heights of 100.5 inches, 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi; and a mean elongation in the range of 14 to 103%.Type: GrantFiled: August 13, 1996Date of Patent: September 23, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Terry L. St. Clair, Catharine C. Fay, Dennis C. Working
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Patent number: 5654541Abstract: A vacuum compatible hyperthermal atom generator includes a membrane having two sides, the membrane having the capability of dissolving atoms into the membrane's bulk. A first housing is furnished in operative association with the first side of the membrane to provide for the exposure of the first side of the membrane to a gas species. A second housing is furnished in operative association with the second side of the membrane to provide a vacuum environment having a pressure of less than 1.times.10.sup.-3 Torr on the second side of the membrane. Exciting means excites atoms adsorbed on the second side of the membrane to a non-binding state so that a portion from 0% to 100% of atoms adsorbed on the second side of the membrane are released from the second side of the membrane primarily as an atom beam.Type: GrantFiled: November 21, 1994Date of Patent: August 5, 1997Assignee: The United States of America as represented by the United States National Aeronautics and Space AdministrationInventors: Ronald A. Outlaw, Mark R. Davidson
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Patent number: 5648432Abstract: In the process of the present invention, a non-polar, aprotic solvent is removed from an oligomer/polymer solution by freeze-drying in order to produce IPNs and semi-IPNs. By thermally quenching the solution to a solid in a short length of time, the size of the minor constituent-rich regions is greatly reduced as they are excluded along with the major constituent from the regions of crystallizing solvent. The use of this process sequence of controlling phase morphology provides IPNs and semi-IPNs with improved fracture toughness, microcracking resistance, and other physical-mechanical properties as compared to IPNs and semi-IPNs formed when the solvent is evaporated rather than sublimed.Type: GrantFiled: June 7, 1995Date of Patent: July 15, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Ruth H. Pater, Marion G. Hansen
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Patent number: 5644022Abstract: Polyimide copolymers were prepared by reacting different ratios of 3,4'-oxydianiline (ODA) and 1,3-bis(3-aminophenoxy)benzene (APB) with 3,3',4,4'-biphenylcarboxylic dianhydride (BPDA), and terminating with an effective amount of a reactive endcapper. The reactive endcappers employed include 4-phenylethynyl phthalic anhydride (PEPA), 3-aminophenoxy-4'-phenylethynylbenzophenone (3-APEB), maleic anhydride (MA) and nadic anhydride (5-norbornene-2,3-dicarboxylic anhydride) (NA). Within a relatively narrow ratio of diamines, from .sup..about. 50% ODA/50% APB to .sup..about. 95% ODA/5% APB, the copolyimides prepared with BPDA and terminated with reactive endgroups have a unique combination of properties that make them very attractive for a number of applications. This unique combination of properties includes low pressure processing (200 psi and below), long term melt stability (several hours at 300.degree. C.Type: GrantFiled: February 14, 1995Date of Patent: July 1, 1997Assignee: The United States of America as represented by the Admninistrator of the National Aeronautics and Space AdministrationInventor: Brian J. Jensen
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Patent number: 5639850Abstract: A process for preparing a tough, soluble, aromatic, thermoplastic copolyimide is provided. The process comprises the steps of (a) providing 4,4'-oxydiphthalic anhydride to 3,4,3',4'-biphenyltetracarboxylic dianhydride at a mole ratio ranging from about 25 mole percent to 75 mole percent to 75 mole percent to about 25 mole percent; (b) adding 3,4'-oxydianiline to form a mixture; c) adding a polar aprotic or polar protic solvent to the mixture to form a solution having a percentage of solids capable of maintaining polymer solubility; (d) stirring the solution to allow it to react; (e) adding an azeotropic solvent to the solution and heating to remove water; (f) cooling the solution of step (e) to room temperature and recovering the tough, soluble, aromatic, thermoplastic copolyimide.Type: GrantFiled: May 18, 1995Date of Patent: June 17, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventor: Robert G. Bryant
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Patent number: 5637670Abstract: Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.Type: GrantFiled: January 20, 1995Date of Patent: June 10, 1997Assignee: The United States of America as represented by the Administrator, National Aeronautics and Space AdministrationInventors: John W. Connell, Paul M. Hergenrother, Joseph G. Smith, Jr.
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Patent number: 5618367Abstract: A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.Type: GrantFiled: April 10, 1995Date of Patent: April 8, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Steven P. Wilkinson, Norman J. Johnston, Joseph M. Marchello
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Patent number: 5606014Abstract: Controlled molecular weight imide oligomers and co-oligomers containing pendent phenylethynyl groups (PEPIs) and endcapped with nonreactive or phenylethynyl groups have been prepared by the cyclodehydration of the precursor amide acid oligomers or co-oligomers containing pendent phenylethynyl groups and endcapped with nonreactive or phenylethynyl groups. The amine terminated amide acid oligomers or co-oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and diamine containing pendent phenylethynyl groups and subsequently endcapped with a phenylethynyl phthalic anhydride or monofunctional anhydride. The anhydride terminated amide acid oligomers and co-oligomers are prepared from the reaction of diamine(s) and diamine containing pendent phenylethynyl group(s) with an excess of dianhydride(s) and subsequently endcapped with a phenylethynyl amine or monofunctional amine. The polymerizations are carried out in polar aprotic solvents such as under nitrogen at room temperature.Type: GrantFiled: August 4, 1995Date of Patent: February 25, 1997Assignee: The United States of America as represented by the United States National Aeronautics and Space AdministrationInventors: John W. Connell, Joseph G. Smith, Jr., Paul M. Hergenrother
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Patent number: 5599993Abstract: Four phenylethynyl amine compounds--3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone--were readily prepared and were used to endcap imide oligomers. Phenylethynyl-terminated amide acid oligomers and phenylethynyl-terminated imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300.degree. C. to 400.degree. C. to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus and good high temperature properties. Adhesive panels, composites, films and moldings from these phenylethynyl terminated imide oligomers gave excellent mechanical performance.Type: GrantFiled: January 20, 1995Date of Patent: February 4, 1997Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Paul M. Hergenrother, Robert G. Bryant, Brian J. Jensen, Stephen J. Havens
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Patent number: 5587041Abstract: A heated shoe and cooled pressure roller assembly for composite prepreg application is provided. The shoe assembly includes a heated forward contact surface having a curved pressure surface. The following cooled roller provides a continuous pressure to the thermoplastic while reducing the temperature to approximately 5.degree. C. below glass transition temperature. Electric heating coils inside the forward portion of the shoe heat a thermoplastic workpiece to approximately 100.degree. C. above the glass transition. Immediately following the heated contact surface, a cooled roller cools the work. The end sharpened shape of the heated shoe trailing edge tends to prevent slag buildup and maintain a uniform, relaxed stress fabrication.Type: GrantFiled: June 1, 1995Date of Patent: December 24, 1996Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Donald A. Sandusky, Joseph M. Marchello
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Patent number: 5585083Abstract: Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.Type: GrantFiled: March 30, 1995Date of Patent: December 17, 1996Assignees: The United States as represented by the Administrator of the National Aeronautics and Space Administration, Rochester Gas & Electric Corp.Inventors: Erik J. Kielin, Kenneth G. Brown, Christine M. D'Ambrosia
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Patent number: 5575955Abstract: An electrically conductive, thermooxidatively stable poltimide, especially a film thereof, is prepared from an intimate admixture of a particular polyimide and gold (III) ions, in an amount sufficient to provide between 17 and 21 percent by weight of gold (III) ions, based on the weight of electrically conductive, thermooxidatively stable polyimide. The particular polyimide is prepared from a polyamic acid which has been synthesized from a dianhydride/diamine combination selected from the group consisting of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2-bis[4-(4 -aminophenoxy)phenyl]hexafluoropropane; 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 4,4'-oxydianiline; 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and 4,4'-oxydianiline; and 3,3'4,4'-benzophenonetetracarboxylic dianhydride and 2,2-bis(3-aminophenyl)hexafluoropropane.Type: GrantFiled: July 22, 1994Date of Patent: November 19, 1996Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Maggie L. Caplan, Diane M. Stoakley, Anne K. St. Clair
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Patent number: 5576488Abstract: A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.Type: GrantFiled: November 21, 1994Date of Patent: November 19, 1996Assignee: The United States of America as represented by the United States National Aeronautics and Space AdministrationInventors: Mark Sheplak, Catherine B. McGinley, Eric F. Spina, Ralph M. Stephens, Purnell Hopson, Jr., Vincent B. Cruz
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Patent number: 5567800Abstract: Controlled molecular weight phenylethynyl terminated imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with phenylethynyl phthalic anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydride(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine.Type: GrantFiled: October 28, 1994Date of Patent: October 22, 1996Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Paul M. Hergenrother, Joseph G. Smith, Jr.
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Patent number: 5554715Abstract: Novel poly(N-arylenebenzimidazole)s (PNABls) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl-N-arylenebenzimidazole) monomers are synthesized by reacting phenyl-4-hydroxybenzoate with bis(2-aminoanilino)arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyI-N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.Type: GrantFiled: January 17, 1995Date of Patent: September 10, 1996Assignee: The United States of America as represented by the Administrator of National Aeronautics and Space AdministrationInventors: John W. Connell, Paul M. Hergenrother, Joseph G. Smith, Jr.