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Results for “heat-resistant polymer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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13 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Heat-resistant polymers containing bipyridyl units. II Polyamide-imides

Polyamide-amic acids containing bipyridyl units were prepared by polymerization of various bipyridyl diamines with trimellitic anhydride acid chloride. These polymers were converted to polyamide-imides by thermal cyclization. The resulting polyamide-imides exhibited very good solubility in organic solvents.

Kurita, K.↗
NASA NTRS1983

Fire- and heat-resistant laminating resins based on maleimido-substituted aromatic cyclotriphosphazenes

A novel class of flame- and heat-resistant polymers has been synthesized by the thermal polymerization of maleimido-substituted aromatic cyclotriphosphazenes. The polymer obtained from tris-(aminophenoxy)tris(maleimidophenoxy)cyclotriphosphazene has good thermal stability and is noteworthy for its high char yield, viz., 82 percent at 800 C in nitrogen and 81 percent at 700 C in air. Graphite-fabric laminates prepared with this polymer did not burn in pure oxygen, even at 300 C, and were tested for mechanical properties. Hexakis(4-maleimidophenoxy)cyclotriphosphazene and some fluorine-containing monomers have also been synthesized. The structures of these cyclic phosphazene precursors and polymers were characterized by FT IR spectrophotometry, H-1 NMR, F-19 NMR, and P-31 solid-state magic angle spinning NMR spectroscopy, and mass spectrometry. The curing behavior of the polymer precursors and the thermal stabilities of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA).

Kumar, D.↗
NASA NTRS2002

NMR Guided Design of Endcaps With Improved Oxidation Resistance

A polyimide is a polymer composed of alternating units of diamine and dianhydride, linked to each other via an imide bond. PMR polyimides, commonly used in the aerospace industry, are generally capped at each end by a norbornene endcap which serves a double function: (1) It limits the number of repeating units and, hence, the average molecular weight of the various polymer chains (oligomers), thereby improving processibility; (2) Upon further treatment (curing), the endcap crosslinks the various oligomer strands into a tough heat-resistant piece. Norbornenyl-end capped PMR polyimide resins' are widely used as polymer matrix composite materials for aircraft engine applications,2 since they combine ease of processing with good oxidative stability up to 300 C. PMR resins are prepared by a twestep approach involving the initial formation of oligomeric pre-polymers capped at both ends by a latent reactive end cap. The end cap undergoes cross-linking during higher temperature processing, producing the desired low density, high specific strength materials, as shown for PMR-15.

Meador, Mary Ann B.↗
NASA NTRS2003

New Endcaps for Improved Oxidation Resistance in PMR Polyimides

A polyimide is a polymer composed of alternating units of diamine and dianhydride, linked to each other via an imide bond. PMR polyimides, commonly used in the aerospace industry, are generally capped at each end by an endcap (such as the nadic endcap used in PMR 15) which serves a double function: (1) it limits the number of repeating units and, hence, the average molecular weight of the various polymer chains (oligomers), thereby improving processibility; (2) Upon further treatment (curing), the endcap crosslinks the various oligomer strands into a tough heat-resistant piece. It is this very endcap, so important to processing, that accounts for much of the weight loss in the polymer on aging in air at elevated temperatures. Understanding this degradation provides clues for designing new endcaps to slow down degradation, and prolong the lifetime of the material.

Frimer, Aryeh A.↗
NASA NTRS2003

Reevaluation of Tetrahydrophthalic Anydrides as Endcaps for Improved Oxidation Resistance in Addition to Polyimides

A polyimide is a polymer composed of alternating units of diamine and dianhydride, linked to each other via an imide bond. PMR polyimides, commonly used in the aerospace industry, are generally capped at each end by an endcap (such as the nadic endcap used in PMR 15) which serves a double function: (1) it limits the number of repeating units and, hence, the average molecular weight of the various polymer chains (oligomers), thereby improving processibility; (2) Upon further treatment (curing), the endcap crosslinks the various oligomer strands into a tough heat-resistant piece. It is this very endcap, so important to processing, that accounts for much of the weight loss in the polymer on aging in air at elevated temperatures. Understanding this degradation provides clues for designing new endcaps to slow down degradation, and prolong the lifetime of the material.

Frimer, Aryeh A.↗
NASA NTRS2011

Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication

In this paper we will discuss a new mass-efficient and innovative way of protecting high-mass spacecraft during planetary Entry, Descent & Landing (EDL). Heat shields fabricated in situ can provide a thermal-protection system (TPS) for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from regolith materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Three regolith processing and manufacturing methods will be discussed: 1) oxygen & metal extraction ISRU processes produce glassy melts enriched in alumina and titania, processed to obtain variable density, high melting point and heat-resistance; 2) compression and sintering of the regolith yield low density materials; 3) in-situ derived high-temperature polymers are created to bind regolith particles together, with a lower energy budget.

Hogue, Michael D.↗
NASA NTRS1988

Fire and heat resistant laminating resin based on maleimido and citraconimido substituted 1-(diorganooxyphosphonyl-methyl)-2,4- and -2,6-diaminobenzenes

The subject invention pertains to a novel class of fire-and heat-resistant bisimide resins prepared by thermal polymerization of maleimido or citraconimido substituded 1-(dialkoxyphosphonyl)-methyl-2-4 and -2,6-diaminobenzenes. Typical polymer presursors have the chemical structure wherein R is alkyl, substituted alkyl or aryl, and R sup 1 is hydrogen or lower alkyl. The polymer precursors are prepared by reacting 1-(diorganooxyphosphonyl)methyl-2-4 and -2,6-diaminobenzenes with maleic anhydride or citraconic anhydride in a mole ratio 1:2. Chains extension of the monomers is achieved by reacting the mono-N-maleimido derivatives of 1-(diorganooxyphosphonyl)methyl-2,4 and -2,6-diaminobenzenes with aryl tetracarboxylic dianhydrides, such as benzophenone tetracarboxylic diandydride, or aryl diisocyanates, such as methylenebis (4-phenylisocyanate), in a mole ratio 2:1. The polymerization of the monomers is studied by differential scanning calorimetry (DSC) and the thermal stability of the polymers is ascertained by thermogravimetric analysis (TGA).

James M Beggs↗
NASA NTRS1989

Ceramic Honeycomb Panels

Ceramic honeycomb panels serve as lightweight, heat-resistant structural members. Depending on choice of ceramic materials, panels expected to withstand temperatures as high as 1,800 degree C. Honeycomb structure made by vapor-depositing ceramic on fabric substrate woven in honeycomb pattern, then eliminating substrate by oxidizing it. Fabric made of loosely woven polymer such as polyacrylonitrile. Impregnated with organic binder such as phenolic resin for stiffness.

Cagliostro, Domenick E.↗