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  • 1
    Electronic Resource
    Electronic Resource
    Thermally stable polyimides from solutions of monomeric reactants (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 905-915 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method to prepare thermally stable resin fiber-reinforced composites using solutions of appropriate monomers is described. Solutions containing a dimethyl ester of an aryl tetracarboxylic acid, the monomethyl ester of 5-norbornene-2,3-dicarboxylic acid and an aryl diamine were used to impregnate graphite fibers. Composites fabricated from these prepregs exhibited excellent thermo-oxidative stability and retention of mechanical properties at 600°F. These results compare favorably with those obtained from composites made from amide-acid prepolymers capped with reactive alicyclic rings. Monomeric solutions provide excellent shelf life and improved solubility compared to amide-acid prepolymer solutions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160409
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    Paper (German National Licenses)
    Fulltext
  • 2
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    In situ polymerization of monomers for high-performance poly/phenylquinoxaline/-graphite fiber composites (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Keywords: CHEMISTRY
    Type: Journal of Applied Polymer Science; 17; 1973
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Tetraglycidyl epoxy resins and graphite fiber composites cured with flexibilized aromatic diamines (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Studies were performed to synthesize new ether modified, flexibilized aromatic diamine hardeners for curing epoxy resins. The effect of moisture absorption on the glass transition temperatures of a tetraglycidyl epoxy, MY 720, cured with flexibilized hardeners and a conventional aromatic diamine was studied. Unidirectional composites, using epoxy-sized Celion 6000 graphite fiber as the reinforcement, were fabricated. The room temperature and 300 F mechanical properties of the composites, before and after moisture exposure, were determined. The Mode I interlaminar fracture toughness of the composites was characterized using a double cantilever beam technique to calculate the critical strain energy release rate.
    Keywords: COMPOSITE MATERIALS
    Type: Polymer Composites (ISSN 0272-8397); 7; 101-105
    Format: text
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  • 4
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    Lower-curing-temperature PMR polyimides (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Partial substitution of a p-aminostyrene end-cap for the monomethyl ester of 5-norbornene-2, 3-dicarboxylic acid lowered the final cure temperature of typical PMR resins from 600 F to 500 F. The weight loss characteristics of neat resins and graphite fiber composites prepared by using the mixed end-cap approach were determined at 600 F. The room temperature and short-time elevated temperature mechanical properties of the composites at 550 F and 600 F were determined. The mechanical property retention characteristics of the composites at 550 F and 600 F are discussed. Previously announced in STAR as N83-10118
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Composites (ISSN 0272-8397); 4; July 198
    Format: text
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  • 5
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    PMR polyimides from solutions containing mixed endcaps (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Previous studies have shown that partial substitution of p-aminostyrene (PAS) for the monomethylester of endo-5-norbornene-2, 3-dicarboxylic acid (NE) lowered the cure temperature of PMR polyimides from 316 to 260 C, but the modified PMR polyimides required higher compression-molding pressures than state-of-the-art PMR-15. In this study PMR polyimides are prepared employing three encaps: NE, PAS, and endo-N-phenyl-5-norbornene-2,3-dicarboximide (PN). The effect of PN addition on the processing characteristics and glass transition temperatures of graphite fiber-reinforced PMR composites is studied. The room temperature and short-time 316 C mechanical properties of the composites are determined. The weight loss and mechanical property retention characteristics of the composites after exposure in air at 316 C are also determined.
    Keywords: NONMETALLIC MATERIALS
    Type: High Temp. Polymer Matrix Composites; p 23-34
    Format: application/pdf
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  • 6
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    Composition and method for making polyimide resin-reinforced fabric (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A composition for making polyimide resin reinforced fibers or fabric is discussed. The composition includes a polyfunctional ester, a polyfunctional amine, and an end capping agent. The composition is impregnated into fibers or fabric and heated to form prepreg material. The tack retention characteristics of this prepreg material are improved by incorporating into the composition a liquid olefinic material compatible with the other ingredients of the composition. The prepreg material is heated at a higher temperature to effect formation of the polyimide resin and the monomeric additive is incorporated in the polyimide polymer structure.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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  • 7
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    Curing agent for polyepoxides and epoxy resins and composites cured therewith (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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  • 8
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    PMR polyimides-review and update (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Fiber reinforced PMR polyimides are finding increased acceptance as engineering materials for high performance structural applications. Prepreg materials based on this novel class of highly processable, high temperature resistant polyimides are commercially available and the PMR concept is used by other investigators. The current status of first and second generation PMR polyimides were reviewed. Emphasis is given to the chemistry, processing and applications of the first generation material known as PMR-15.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-82821 , E-1111 , NAS 1.15:82821 , AVRADCOM-TR-82-C-3
    Format: application/pdf
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  • 9
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    Preparation of polyimides from mixtures of monomeric diamines and esters of polycarboxylic acids (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Polyimides having high thermal and oxidative stability are prepared by the reaction of a mixture of monomers comprising (1) a dialkyl or tetraalkyl ester of an aromatic tetracarboxylic acid; (2) an aromatic diamine; and (3) a monoalkyl or dialkyl ester of a dicarboxylic acid where in the ratio of a:b:c is n:(n+1):2, wherein n has a value from 1 to 20. The mixture of monomers is prepared in a 30 to 70 percent by weight solution of an organic solvent, a substrate impregnated with the solution and heated at 50 to 205 C to remove said solvent and form a low molecular weight prepolymer, and thereafter heated at 275 to 350 C to cure to a high molecular weight polyimide.
    Keywords: CHEMISTRY
    Format: application/pdf
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  • 10
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    Addition-type polyimides from solutions of monomeric reactants (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The monomeric reactants approach was used to fabricate addition-type polyimide/graphite fiber composites with improved mechanical properties and thermal stability characteristics over those of composites derived from addition-type amide acid prepolymers. A screening study of 24 different monomer combinations was performed. The results of a more extensive investigation of a selected number of monomer combinations showed that the combination providing the best thermomechanical properties was 5-norbornene-2,3-dicarboxylic acid monomethyl ester/4,4'-methylenedianiline/3,3'4,4'-benzophenone tetracarboxylic acid dimethyl ester at a molar ratio of 2/3.09/2.09.
    Keywords: MATERIALS, NONMETALLIC
    Type: NASA-TN-D-6877 , E-6750
    Format: application/pdf
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