Patents by Inventor Charles W. Stewart
Charles W. Stewart has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5266639Abstract: Copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) having high HFP content and end-of-melting temperature, T.sub.m (end), as low as 200.degree. C. are disclosed. Exceptional performance as a processing aid in polyolefins results from having T.sub.m (end) of the TFE/HFP copolymer close to the processing temperature of the polyolefin. These TFE/HFP copolymers are soluble in fluorinated cyclic solvents. Copolymer/solvent systems copolymer at significant concentrations in selected solvents are fluid and stable at room temperature.Type: GrantFiled: August 28, 1992Date of Patent: November 30, 1993Assignee: E. I. Du Pont de Nemours and CompanyInventors: George R. Chapman, Jr., Lewis E. Crenshaw, Rita S. McMinn, Richard A. Morgan, Donnan E. Priester, Charles W. Stewart, William H. Tuminello, Robert E. Tarney, John G. Van Alsten, Mark E. Wagman
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Patent number: 5185116Abstract: Extruded shaped structures of amorphous polyarylate copolymers, having a tensile elongation at break of at least 80% at 25.degree. C., are made by drawing a molten extrudate of the copolymer at a temperature at least 100.degree. C. above the glass transition temperature of the copolymer.Type: GrantFiled: June 14, 1991Date of Patent: February 9, 1993Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 5132368Abstract: The subject invention provides a composition having excellent extrusion characteristics comprising a difficulty-melt-processible polymer and 0.002-0.5 wt. % of one or more fluoropolymer process aids wherein the fluoropolymer has a fluorine to carbon ratio of at least 1:2, is capable of forming a die-coating film under the prevailing conditions of extrusion temperature and pressure, and contains an effective amount of polar functional polymer chain end groups, --W, wherein --W is selected from --COF, --SO.sub.2 F, --SO.sub.3 M, --OSO.sub.3 M, --COOR, and --COOM, wherein R is C.sub.1-3 alkyl and M is hydrogen, a metal cation, preferably an alkali or alkaline earth metal cation, or a quaternary ammonium cation.Type: GrantFiled: September 3, 1991Date of Patent: July 21, 1992Assignee: E. I. Du Pont de Nemours and CompanyInventors: George R. Chapman, Jr., Donnan E. Priester, Charles W. Stewart, Robert E. Tarney
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Patent number: 5064704Abstract: Extruded shaped structures of amorphous polyarylate copolymers, having a tensile elongation at break of at least 80% at 25.degree. C., are made by drawing a molten extrudate of the copolymer at a temperature at least 100.degree. C. above the glass transition temperature of the copolymer.Type: GrantFiled: September 29, 1989Date of Patent: November 12, 1991Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 5057575Abstract: Polymer blend composition having improved processibility and comprising:(a) a major portion of a difficultly melt-procesible polymer, and(b) a minor portion of:1 at least an effective amount, to improve processibility, of a fluorocarbon copolymer which at the melt-processing temperature of (a) is either in a melted form if crystalline, or is above its glass transition temperature if amorphous, and(2) at least an effective amount, to improve processibility, of at least one tetrafluoroethylene homopolymer or copolymer of tetrafluoroethylene and at least one monomer copolymerizable therewith, wherein the mole ratio of fluorine to hydrogen is at least 1:1, and which is solid at the melt-processing temperature of (a);masterbatches comprised of the processing aid; and processes utilizing the processing aid.Type: GrantFiled: February 1, 1991Date of Patent: October 15, 1991Assignee: E. I. Du Pont de Nemours and CompanyInventors: George R. Chapman, Jr., Donnan E. Priester, Charles W. Stewart
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Patent number: 5051479Abstract: A melt-processable thermoplastic composition consisting essentially of a blend of a melt processable thermoplastic fluorocarbon polymer and about 0.05 to about 0.5 percent by weight of an elastomeric copolymer of tetrafluoroethylene and a perfluoro(alkyl vinyl ether) exhibits improved processing properties.Type: GrantFiled: April 3, 1989Date of Patent: September 24, 1991Assignee: E. I. Du Pont de Nemours and CompanyInventors: Anestis L. Logothetis, Charles W. Stewart
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Patent number: 5013792Abstract: Polymer blend composition having improved processibility and comprising:(a) a major portion of a difficultly melt-processible polymer, and(b) a minor portion of:(1) at least an effective amount, to improve processibility, of a fluorocarbon copolymer which at the melt-processing temperature of (a) is either in a melted form if crystalline, or is above its glass transition temperature if amorphous, and(2) at least an effective amount, to improve processibility, of at least one tetrafluoroethylene homopolymer or copolymer of tetrafluoroethylene and at least one monomer copolymerizable therewith, wherein the mole ratio of fluorine to hydrogen is at least 1:1, and which is solid at the melt-processing temperature of (a);masterbatches comprised of the processing aid; and processes utilizing the processing aid.Type: GrantFiled: August 29, 1990Date of Patent: May 7, 1991Assignee: E. I. Du Pont de Nemours and CompanyInventors: George R. Chapman, Jr., Donnan E. Priester, Charles W. Stewart
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Patent number: 4963609Abstract: A low smoke and flame-resistant fluoropolymer composition, useful as insulation in a plenum cable and comprised of a base polymer of ethylene units, tetrafluoroethylene and/or chlorotrifluoroethylene units, and fluorine-containing, non-telogenic termonomer units; a metal oxide; and a polytetrafluoroethylene drip suppressant.Type: GrantFiled: November 1, 1989Date of Patent: October 16, 1990Assignee: E. I. Du Pont de Nemours and CompanyInventors: Jerrel C. Anderson, Subhash V. Gangal, Dewey L. Kerbow, Charles W. Stewart
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Patent number: 4952630Abstract: Dispersion-process-produced, non-melt-processible, particulate, core-shell, tetrafluoroethylene copolymer comprising recurring units of tetrafluoroethylene and modifying recurring units of at least one ethylenically unsaturated comonomer that is copolymerizable with the tetrafluoroethylene, the number of recurring units of comonomer in the shell being sufficient to enable the copolymer to compound uniformly with an elastomer or plastic without forming visible agglomerates, and blends thereof with elastomeric and plastic resins.Type: GrantFiled: November 6, 1989Date of Patent: August 28, 1990Assignee: E. I. Du Pont de Nemours and CompanyInventors: Richard A. Morgan, Charles W. Stewart
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Patent number: 4952636Abstract: Dispersion-process-produced, non-melt-processible, particulate, core-shell, tetrafluoroethylene copolymer comprising recurring units of tetrafluoroethylene and modifying recurring units of at least one ethylenically unsaturated comonomer that is copolymerizable with the tetrafluoroethylene, the number of recurring units of comonomer in the shell being sufficient to enable the copolymer to compound uniformly with an elastomer or plastic without forming visible agglomerates, and blends thereof with elastomeric and plastic resins.Type: GrantFiled: November 6, 1989Date of Patent: August 28, 1990Assignee: E. I. du Pont de Nemours and CompanyInventors: Richard A. Morgan, Charles W. Stewart
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Patent number: 4912166Abstract: A blend of tetrafluoroethylene and a poly(oxy-p-phenyleneisophthaloyl-phenylene/oxy-p-phenyleneterephthaloyl- p-phenylene) (PEKK) results in improved processing of the fluoroelastomer at temperatures below the melting temperature of the PEKK and improves physical properties of cured fluoroelastomer.Type: GrantFiled: October 26, 1988Date of Patent: March 27, 1990Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 4904726Abstract: Dispersion-process-produced, non-melt-processible, particulate, core-shell, tetrafluoroethylene copolymer comprising recurring units of tetrafluoroethylene and modifying recurring units of at least one ethylenically unsaturated comonomer that is copolymerizable with the tetrafluoroethylene, the number of recurring units of comonomer in the shell being sufficient to enable the copolymer to compound uniformly with an elastomer or plastic without forming visible agglomerates, and blends thereof with elastomeric and plastic resins.Type: GrantFiled: December 9, 1988Date of Patent: February 27, 1990Assignee: E. I. DuPont DeNemours and CompanyInventors: Richard A. Morgan, Charles W. Stewart
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Patent number: 4772654Abstract: It has now been discovered that a selected magnesium oxychloride can be mixed with a thermoplastic polymer sensitive to decomposition by water, such as polyamides or polyesters, or with fluoropolymers.Type: GrantFiled: July 21, 1987Date of Patent: September 20, 1988Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 4713418Abstract: A composition and method for preparing it is disclosed. The composition in a blend of a cured fluoroelastomer which except for the cure sites is a perfluorocarbon and a thermoplastic copolymer of tetrafluoroethylene which is present as generally spherical particles having a particle size of less than 10 microns. The composition is prepared by blending the fluoroelastomer and thermoplastic copolymer at a temperature above the melting point of the thermoplastic copolymer followed by curing the fluoroelastomer.Type: GrantFiled: December 6, 1985Date of Patent: December 15, 1987Assignee: E. I. Du Pont De Nemours and CompanyInventors: Anestis L. Logothetis, Charles W. Stewart
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Patent number: 4596855Abstract: An elastomeric composition comprising an elastomer matrix having dispersed therein about 3-30 parts per 100 parts by weight of the elastomer of powdered polytetrafluoroethylene having a number average molecular weight of at least about 250,000 and a surface area of at least 1 m.sup.2 /g which has been treated with about 50-120% of sodium-naphthalene addition compound or another addition compound of an alkali metal required for the alkali metal to react with all the fluorine atoms on the surface of the polytetrafluoroethylene powder.By dispersing such treated polytetrafluoroethylene powder in elastomer matrix, one increases significantly the tear strength of the elastomer, while increasing its modulus only moderately. In this way, the processability of the elastomeric compositions is not adversely affected.Type: GrantFiled: December 4, 1984Date of Patent: June 24, 1986Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 4507439Abstract: An elastomeric composition comprising an elastomer matrix having dispersed therein about 3-30 parts per 100 parts by weight of the elastomer of powdered polytetrafluoroethylene having a number average molecular weight of at least about 250,000 and a surface area of at least 1 m.sup.2 /g which has been treated with about 50-120% of sodium-naphthalene addition compound or another addition compound of an alkali metal required for the alkali metal to react with all the fluorine atoms on the surface of the polytetrafluoroethylene powder.By dispersing such treated polytetrafluoroethylene powder in elastomer matrix, one increases significantly the tear strength of the elastomer, while increasing its modulus only moderately. In this way, the processability of the elastomeric compositions is not adversely affected.Type: GrantFiled: November 28, 1983Date of Patent: March 26, 1985Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 4503171Abstract: Graphite particularly suitable for compounding with perfluoroelastomers having grafted thereto reactive sites having a fluorinated aromatic ring. The perfluoroelastomer blends exhibit markedly improved tensile strength while retaining the outstanding thermal and chemical stability of the perfluoroelastomers.Type: GrantFiled: January 11, 1984Date of Patent: March 5, 1985Assignee: E. I. Du Pont de Nemours and CompanyInventor: Charles W. Stewart
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Patent number: 4503192Abstract: Blends of elastomers of chlorinated or chlorosulfonated polyethylene and ultra high molecular weight, i.e. at least one million, when cured with conventional curing systems for the chlorinated or chlorosulfonated polyethylene have higher tear strengths at temperatures of about 150.degree. C. than do the unblended elastomers. The amount of polyethylene in the blend is 5 to 50 parts by weight per 100 parts by weight of elastomer. The blend, thus produced has a modulus (M.sub.100) of greater than 1000 psi prior to curing.Type: GrantFiled: January 6, 1984Date of Patent: March 5, 1985Assignee: E. I. Du Pont de Nemours and CompanyInventors: Herbert F. McShane, Jr., Peter N. Plimmer, Charles W. Stewart
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Patent number: 4469846Abstract: Core/shell fluoropolymer compositions in particulate form, wherein the core is a highly crystalline polymer such as, for example, tetrafluoroethylene, and the shell is an elastomeric fluoropolymer such as, for example, a vinylidene fluoride/hexafluoropropene copolymer, optionally also containing a cure site monomer are outstanding additives for uncured fluoroelastomer compositions, which after curing in the presence of dispersed core/shell fluoropolymers have improved tear strength, tear strength to modulus ratio, and certain other physical properties.Type: GrantFiled: May 20, 1983Date of Patent: September 4, 1984Assignee: E. I. Du Pont de Nemours and CompanyInventors: Ausat A. Khan, Charles W. Stewart
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Patent number: 4294489Abstract: Flame resistance of upholstered furniture is significantly improved by interposing between the cover fabric and the padding or applying to the top side of the cover fabric a layer of neoprene foam capable of forming when exposed to a burning cigarette or under the conditions of a standard flame spread test, a thermally insulating char which does not smolder, and which maintains its structural integrity. The neoprene foam must be so formulated that it also is capable of evolving at combustion temperature sufficient amount of water to efficiently cool the affected area. Normally, the latex from which the foam is prepared is formulated with a char promoter and a hydrated inorganic compound. Upholstered furniture of this invention passes a burning cigarette test and performs extremely well in the flame spread test.Type: GrantFiled: March 13, 1978Date of Patent: October 13, 1981Assignee: E. I. Du Pont de Nemours and CompanyInventors: Colin Anolick, Vivian M. Robinson, Charles W. Stewart, Sr.