Patents by Inventor George M. Fohlen

George M. Fohlen 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).

  • Patent number: 4748263
    Abstract: 4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g. hexakis amino or trisaminophenoxy-trisphenoxy-cyclotriphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yields and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics.
    Type: Grant
    Filed: October 29, 1986
    Date of Patent: May 31, 1988
    Assignee: The United States of America as represented by the administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4668589
    Abstract: Aminophenoxycyclotriphosphazenes such as hexakis(4-aminophenoxy)cyclotriphosphazene and tris(4-aminophenoxy)-tris phenoxyclyclotriphosphazene are used as curing agents for epoxy resins. These 1,2-epoxy resins are selected from di- or polyepoxide-containing organic moieties of the formula (CH.sub.2 --CHO--CH.sub.2).sub.m --W--R--W--(CH.sub.2 CH--CH.sub.2 O).sub.m where R is diphenyldimethylmethane, diphenylmethane, bis(dibromophenyl)dimethylmethane, or ##STR1## W is a nitrogen or oxygen atom; and m is 1 when W is oxygen and 2 when W is nitrogen. The resins are cured thermally in stages at between about 110.degree. to 135.degree. C. for between about 1 and 10 min, then at between about 175.degree. to 185.degree. C. for between about 0.5 to 10 hr and post-cured at between about 215.degree. and 235.degree. C. for between abut 0.1 and 2 hr. These resins are useful for making fire-resistant elevated temperature stable composites, laminates (e.g.
    Type: Grant
    Filed: November 21, 1985
    Date of Patent: May 26, 1987
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4649189
    Abstract: Imide-linked bisphthalonitrile compounds are prepared by combining a dicyano aromatic diamine and an organic dianhydride to produce an amic acid linked bisphthalonitrile copound. The amic acid linked bisphthalonitrile compound is dehydrocyclized to produce the imide-linked bisphthalonitrile compounds. The imide-linked bisphthalonitrile compounds may be polymerized to produce a phthalocyanine polymer by heating the imide-linked bisphthalonitrile compound, either alone or in the presence of a metal powder or a metal salt. These compounds are useful in the coating, laminating and molding arts. The polymers are useful in composite matrix resins where increased fire resistance, toughness and resistance to moisture are required, particularly as secondary structures in aircraft and spacecraft.
    Type: Grant
    Filed: July 12, 1985
    Date of Patent: March 10, 1987
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4634759
    Abstract: 4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g. hexakis amino or trisaminophenoxy-trisphenoxy-cyclotriphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yeilds and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics.
    Type: Grant
    Filed: July 30, 1985
    Date of Patent: January 6, 1987
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4600769
    Abstract: Novel amine terminated bisaspartimides, especially 4,4'-bis{N.sup.2 -[4-(4-aminophenoxy)phenyl]aspartimido} diphenylmethane are prepared by a Michael-type reaction of an aromatic bismaleimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers cross-linked through --NH-- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures, e.g., as lightweight laminates with graphite cloth, molding material prepregs, adhesives and insulating material.
    Type: Grant
    Filed: May 31, 1985
    Date of Patent: July 15, 1986
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4579782
    Abstract: Novel amine terminated bisaspartimides, especially 4,4'-bis{N.sup.2 -[4-(4-aminophenoxy)phenyl]aspartimido}diphenylmethane are prepared by a Michael-type reaction of an aromatic bismaleimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers cross-linked through --NH-- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures, e.g., as lightweight laminates with graphite cloth, molding material prepregs, adhesives and insulating material.
    Type: Grant
    Filed: August 30, 1985
    Date of Patent: April 1, 1986
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4550177
    Abstract: 4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g. hexakis amino or trisaminophenoxy-trisphenoxy-cyclotriphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yields and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics.
    Type: Grant
    Filed: April 11, 1984
    Date of Patent: October 29, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Devendra Kumar, George M. Fohlen, John A. Parker
  • Patent number: 4537834
    Abstract: Metal, preferably divalent copper, cobalt or nickel, phthalocyanine tetraamines are used as curing agents for epoxides. The resulting copolymers have high thermal and chemical resistance and are homogeneous. They are useful as binders for laminates, e.g. graphite cloth laminate.
    Type: Grant
    Filed: April 11, 1984
    Date of Patent: August 27, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4522755
    Abstract: Metal 4, 4', 4", 4"'-tetracarboxylic phthalocyanines (MPTC) are prepared by reaction of trimellitic anhydride, a salt or hydroxide of the desired metal (or the metal in powdered form), urea and a catalyst. A purer form of MPTC is prepared than heretofore. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35.ANG..
    Type: Grant
    Filed: September 15, 1983
    Date of Patent: June 11, 1985
    Assignee: The United States of America as represented by the United States National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4499260
    Abstract: Method of forming 4,4',4",4'"-tetraamino phthalocyanines by reducing 4,4',4",4'"-tetranitro phthalocyanines, polymerization of the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerization with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, etc.
    Type: Grant
    Filed: November 10, 1982
    Date of Patent: February 12, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4496701
    Abstract: Cured polymers of bis- and tris-imides derived from tris(m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, and addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride prior to curing are disclosed and claimed. Such polymers are flame resistant. Also disclosed are an improved method of producing tris(m-aminophenyl) phosphine oxides from the nitro analogues by reduction with hydrazine hydrate using palladized charcoal or Raney nickel as the catalyst and fiber-reinforced cured resin composites.
    Type: Grant
    Filed: June 9, 1983
    Date of Patent: January 29, 1985
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Indra K. Varma, George M. Fohlen, John A. Parker
  • Patent number: 4450268
    Abstract: The invention relates to metal, primarily divalent metal such as divalent copper, cobalt and nickel, 4,4',4", 4'" phthalocyanine tetracarboxylic acids and to polymers prepared by heating the same, and to a method of preparing the tetracarboxylic acids.A method is provided for preparing the aforesaid tetracarboxylic acids in purer form than heretofore. Upon heating these acids decarboxylate and produce polymers.These polymers have diphenyl (conjugated) types of linkage; they are thermally and oxidatively stable and useful as sheet polymers for various purposes such as heat shielding.The monomeric tetracarboxylic acid is shown in FIG. 1, the polymer in FIG. 2 and thermal resistance in FIG. 3.The monomeric tetracarboxylic acids are prepared in purer form than heretofore, the resulting polymers are more stable thermally and oxidatively than metal phthalocyanine polymers and monomers heretofore made.
    Type: Grant
    Filed: September 8, 1982
    Date of Patent: May 22, 1984
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Bappalige N. Achar, George M. Fohlen, John A. Parker
  • Patent number: 4433115
    Abstract: Flame-resistant reinforced bodies are disclosed which are composed of reinforcing fibers, filaments or fabrics in a cured body of bis- and tris-imide resins derived from tris(m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, or of addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride.
    Type: Grant
    Filed: July 11, 1983
    Date of Patent: February 21, 1984
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Indra K. Varma, George M. Fohlen, John A. Parker
  • Patent number: 4421820
    Abstract: Phosphine oxide-containing polyimide resins modified by elastomers, having improved mechanical properties and particularly useful in the production of fiber or fabric-reinforced composites or laminates.
    Type: Grant
    Filed: November 15, 1982
    Date of Patent: December 20, 1983
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Indra K. Varma, George M. Fohlen, John A. Parker
  • Patent number: 4395557
    Abstract: Bis- and tris-imides derived from tris(m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, and addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride. Such monomers or their oligomers may be used to impregnate fibers and fabrics which when cured, are flame resistant. Also an improved method of producing tris(m-aminophenyl) phosphine oxides from the nitro analogues by reduction with hydrazine hydrate using palladized charcoal or Raney nickel as the catalyst.
    Type: Grant
    Filed: July 30, 1981
    Date of Patent: July 26, 1983
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventors: Indra K. Varma, George M. Fohlen, John A. Parker
  • Patent number: 4276344
    Abstract: Fire-resistant resins particularly useful for making laminates with inorganic fibers such as graphite fibers, are made by (1) condensation of an ethylenically unsaturated cyclic anhydride with a bis(diaminophenyl)phosphine oxide, and (2) by addition polymerization of the bisimide so obtained. Up to about 50%, on a molar basis, of benzophenonetetracarboxylic acid anhydride can be substituted for some of the cyclic anhydride to alter the properties of the products. Graphite cloth laminates made with these resins have shown 800.degree. C. char yields greater than 70% by weight in nitrogen. Limiting oxygen indexes (LOI) of more than 100% have been determined for these resins, as per ASTM D 2863-4.
    Type: Grant
    Filed: August 5, 1980
    Date of Patent: June 30, 1981
    Inventors: Indra K. Varma, George M. Fohlen, John A. Parker, Robert A. Frosch