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  • 1
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    Synthesis of perfluoroalkylether triazine elastomers (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A method of perfluoroalkylether triazine elastomer synthesis is described. To form an elastomer, the resultant polymer is heated in a closed oven at slightly reduced pressures for 1-day periods at 100, 130 and 150 C. A high-molecular-weight perfluoroalkylether triazine elastomer is produced that exhibits thermal and oxidative stability. This material is potentially useful in applications such as high-temperature seals, 'O' rings, and wire enamels.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Polymer Science; vol. 18
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Advanced Strain-Isolation-Pad Material with Bonded Fibrous Construction (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of utilizing air lay and liquid lay felt deposition techniques to fabricate strain isolation pad (SIP) materials for the Space Shuttle Orbiter was demonstrated. These materials were developed as candidate replacements for the present needled felt SIP used between the ceramic tiles and the aluminum skin on the undersurface of the Orbiter. The SIP materials that were developed consisted of high temperature aramid fibers deposited by controlled fluid (air or liquid) carriers to form low density unbonded felts. The deposited felts were then bonded at the fiber intersections with a small amount of high temperature polyimide resin. This type of bonded felt construction can potentially eliminate two of the problems associated with the present SIP, viz., transmittal of localized stresses into the tiles and load history dependent mechanical response. However, further work is needed to achieve adequate through thickness tensile strength in the bonded felts.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-166599 , NAS 1.26:166599
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Process for preparing perfluorotriazine elastomers and precursors thereof (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Perfluoroether triazine elastomers having improved properties and utility in seals, gaskets, sealing components and the like are prepared from oligomeric imidoylamidines that have, in turn, been prepared by the process of (1) reacting a perfluorodinitrile with liquid ammonia to yield a perfluorodiamidine, (2) isolating the perfluorodiamidine, (3) reacting the isolated diamidine with a perfluorodinitrile to yield a perfluoror(imidoylamidine) dinitrile, and then repeating step (1), (2), and (3) to sequentially grow an oligomer of desired molecular size. The isolated amidine and nitrile intermediates are also described.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Chemical approach for controlling nadimide cure temperature and rate (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300 C by controlling the available concentration of the maleic capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic capped reactant.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    The 1,2,4-oxadiazole elastomers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Crosslinked 1,2,4-oxadiazole elastomers were prepared either by thermally condensing a monomer having the formula HwN(HON)C-R-Q, wherein Q is a triazine ring forming group such as nitrile or amidine, or by a mixture of said monomer with RC(NOH)NH22, with R in these formulas standing for a bivalent organic radical containing fluorine, hydrogen, or trifluoromethyl. In the monomer charge, the overall proportions of amidoxime groups to triazine ring forming groups varies depending on the extent of crosslinking desired in the final polymer. The heat and chemical resistant elastomers disclosed can serve, for instance, as adhesives, caulking compounds, channel sealants, fuel tank liners.
    Keywords: NONMETALLIC MATERIALS
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  • 6
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    Process for the preparation of fluorine containing crosslinked elastomeric polytriazine and product so produced (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Crosslinking elastomeric polytriazines are prepared by a 4 step procedure which consists of (1) forming a poly(imidoylamidine) by the reaction, under reflux conditions, of anhydrous ammonia with certain perfluorinated alkyl or alkylether dinitriles; (2) forming a linear polytriazine by cyclizing the imidoylamidine linkages by reaction with certain perfluorinated alkyl or alkylether acid anhydrides or halides; (3) extending the linear polytriazine chain by further refluxing in anhydrous ammonia; and (4) heating to cyclize the new imidoylamidine and thereby crosslink the polymer.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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  • 7
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    Analyses of moisture in polymers and composites (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A suitable method for the direct measurement of moisture concentrations after humidity/thermal exposure on state of the art epoxy and polyimide resins and their graphite and glass fiber reinforcements was investigated. Methods for the determination of moisture concentration profiles, moisture diffusion modeling and moisture induced chemical changes were examined. Carefully fabricated, precharacterized epoxy and polyimide neat resins and their AS graphite and S glass reinforced composites were exposed to humid conditions using heavy water (D20), at ambient and elevated temperatures. These specimens were fixtured to theoretically limit the D20 permeation to a unidirectional penetration axis. The analytical techniques evaluated were: (1) laser pyrolysis gas chromatography mass spectrometry; (2) solids probe mass spectrometry; (3) laser pyrolysis conventional infrared spectroscopy; and (4) infrared imaging thermovision. The most reproducible and sensitive technique was solids probe mass spectrometry. The fabricated exposed specimens were analyzed for D20 profiling after humidity/thermal conditioning at three exposure time durations.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-159745 , TRW-31782-6082-RU-00
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    High performance channel injection sealant invention abstract (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: High performance channel sealant is based on NASA patented cyano and diamidoximine-terminated perfluoroalkylene ether prepolymers that are thermally condensed and cross linked. The sealant contains asbestos and, in its preferred embodiments, Lithofrax, to lower its thermal expansion coefficient and a phenolic metal deactivator. Extensive evaluation shows the sealant is extremely resistant to thermal degradation with an onset point of 280 C. The materials have a volatile content of 0.18%, excellent flexibility, and adherence properties, and fuel resistance. No corrosibility to aluminum or titanium was observed.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Bifunctional monomers having terminal oxime and cyano or amidine groups (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The preparation of crosslinked 1,2,4-oxadiazole elastomers is described. The technique involves thermally condensing (1) a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming groups such as nitrile or amidine or a mixture of such group with amidoxime, or (2) a mixture of the same monomer with R(C(NOH)NH2)2, with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Preparation of crosslinked 1,2,4-oxadiazole polymer (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: New crosslinked 1,2,4-oxadiazole elastomers were prepared by thermally condensing a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming group such as nitrile or amidine or a mixture of such group with amidoxime, or a mixture of said monomer with R C(NOH)NH2 sub 2 with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer.
    Keywords: NONMETALLIC MATERIALS
    Format: application/pdf
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