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  • 1
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    Poly(ether imide)s from Diamines withPara-,Meta-, andOrtho-Arylene Substitutions: Synthesis, Characterization, and Liquid Crystalline Properties (2008)
    American Chemical Society
    Details
    Publication Date: 2008-04-01
    Print ISSN: 0024-9297
    Electronic ISSN: 1520-5835
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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    PAPER CURRENT
  • 2
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    Wholly Aromatic Ether-imides. Potential Materials for n-Type Semiconductors (2004)
    American Chemical Society
    Details
    Publication Date: 2004-03-01
    Print ISSN: 0897-4756
    Electronic ISSN: 1520-5002
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by American Chemical Society
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    PAPER CURRENT
  • 3
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    Evaluation of two bisimide additives in LARC-TPI adhesive (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The processability of aromatic polyimides can be improved by the addition of bis (amide) acids or bisimides to LARC-TPI. These low molecular weight additives apparently lower the melt viscosity of aromatic polyimides without affecting the glass transition temperature. Well-consolidated, fiber reinforced composites were fabricated using this technology. LARC-TPI can be processed as a thermoplastic polyimide to form high strength bonds, however, this is generally accomplished by processing at relatively high bonding pressures. An adhesive investigation is presented on the effects of two bisimide additives to LARC-TPI in an attempt to improve the bonding process by lowering the viscosity of the material to achieve improved bond strength properties. Apparently, the high flow which is exhibited by the additives when they melt, tended to be masked by the more viscous LARC-TPI.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-102742 , NAS 1.15:102742
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Adhesive evaluation of new polyimides (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: During the past 10 to 15 years, the Materials Division at NASA Langley Research Center (LaRC) has developed several novel high temperature polyimide adhesives for anticipated needs of the aerospace industry. These developments have resulted from fundamental studies of structure-property relationships in polyimides. Recent research at LaRC has involved the synthesis and evaluation of copolyimides which incorporate both flexibilizing bridging groups and meta-linked benzene rings. The purpose was to develop systems based on low cost, readily available monomers. Two of these copolyimides evaluated as adhesives for bonding titanium alloy, Ti(6Al-4V), are identified as LARC-STPI and STPI-LARC-2. Lap shear strength (LSS) measurements were used to determine the strength and durability of the adhesive materials. LSS results are presented for LARC-TPI and LARC-STPI lap shear specimens thermally exposed in air at 232 C for up to 5000 hrs. LARC-TPI was shown to perform better than the copolymer LARC-STPI which exhibited poor thermooxidative performance possibly due to the amines used which would tend to oxidize easier than the benzophenone system in LARC-TPI.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-89140 , NAS 1.15:89140
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Semi-2-interpenetrating networks of high temperature systems (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A semi-2-interpenetrating network of improved qualities which is prepared by combining a linear polymer and a cross-linkable oligomer having identical repeating units is developed. Polymers have been combined in the past into interpenetrating networks in order to gain useful properties from the combination of materials. However, previous semi-interpenetrating networks have only been formed using polymers having different repeating units. This method provides a semi-2-interpenetrating network of improved strength, adhesion, and processability.
    Keywords: NONMETALLIC MATERIALS
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    NASA TECHNICAL REPORTS
  • 6
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    Thermoplastic adhesives based on 4,4'-isophthaloyldiphthalic anhydride (IDPA) (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Thermoplastic polyimides were prepared and evaluated as adhesives. These materials are based on 4,4'-isophthaloyldiphathalic anhydride (IDAP) and either metaphenylene diamine (MPD) or 3,3'-diaminobenzophenone (DBAP). Both polymers exhibit excellent adhesive properties; however, the IDPA-MPD is the more attractive system because of a combination of high mechanical and physical properties as well as being made from commercially attractive monomers. The IDPA-MPD is an isomeric form of the commercially available adhesive and matrix resin, LARC-TPI and both systems have the same glass transition temperature and exhibit similar adhesive properties.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-101508 , NAS 1.15:101508
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    High performance composites research at NASA-Langley (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Barriers to the more extensive use of advanced composites in heavily loaded structures on commercial transports are discussed from a materials viewpoint. NASA-Langley matrix development activities designed to overcome these barriers are presented. These include the synthesis of processible, tough, durable matrices, the development of resin property/composite property relationships which help guide the synthesis program, and the exploitation of new processing technology to effectively combine reinforcement filament with polymer matrices. Examples of five classes of polymers being investigated as matrix resins at NASA Langley are presented, including amorphous and semicrystalline thermoplastics, lightly crosslinked thermoplastics, semi-interpenetrating networks and toughened thermosets. Relationships between neat resin modulus, resin fracture energy, interlaminar fracture energy, composite compression strength, and post-impact compression strength are shown. Powder and slurry processing techniques are discussed.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-100518 , NAS 1.15:100518
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Copolyimide with a combination of flexibilizing groups (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Copolyimides are prepared by reacting one or more aromatic dianhydrides with a meta-substituted phenylene diamine and an aromatic bridged diamine. The incorporation of meta-substituted phenylene diamine derived units and bridged aromatice diamine derived units into the linear aromatic polymer backbone results in a copolyimide of improved flexibility, processability, and melt-flow characteristics. The copolyimides are especially useful as thermoplastic hot-melt adhesives.
    Keywords: NONMETALLIC MATERIALS
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    NASA TECHNICAL REPORTS
  • 9
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    LARC-IA: A flexible backbone polyimide (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A new linear, aromatic, thermoplastic polyimide, prepared from oxydiphthalic anhydride (ODPA) and 3,4'-oxydianiline (ODA) in diglyme and identified as LARC-IA, was synthesized and evaluated. The monomers are relatively inexpensive and physiologically safe. Molecular weight was controlled by use of a monofunctional anhydride, phthalic anhydride (PA), in order to promote controlled flow and wetting properties. The polymer is considered a safe alternative to commercially available LARC-TPI which is prepared with an expensive diamine of uncertain carcinogenicity. The evaluation was based primarily on the polymer's adhesive properties as determined by thermal and water boil exposure of lap shear specimens. Strengths were determined at room temperature, 177, 204 and 232 C before and after exposure to determine the adhesive system's durability to adverse environments over a period of time. Other properties (FWT, G(1c), film and composite properties) were examined which were determined to be typical of a high temperature polyimide. Results of the study show a favorable comparison to LARC-TPI, a commercially available polyimide.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-102586 , NAS 1.15:102586
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Isomeric oxydiphthalic anhydride polyimides (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Much of the polyimide research at Langley Research Center has focused on isomeric modification of the diamine component; polyimides having considerably improved processability and adhesion have resulted. The present structure-property study was designed to investigate how isomeric attachment of the three oxydiphthalic anhydride (ODPA) polyimides affects their properties. Each dianhydride, 3,4,3',4'-oxydiphthalic anhydride (4,4'-OPDA,I), 2,3,2',3'-oxydiphthalic anhydride (3,3'-ODPA,II), and 2,3,3',4'-oxydiphthalic anhydride (3,4'-OPDA,III), was reacted with p-phenylenediamine, 4,4'-oxydianiline, 3,3'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 4,4'-bis(3-aminophenoxy)benzophenone in DMAc. The inherent viscosities of the resulting poly(amic acids) were determined. Thermally imidized films were studied for their creasability and solubility, as well as by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide angle X-ray scattering (WAXS). A comparison of these properties will be made.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-101525 , NAS 1.15:101525
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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