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  • 1
    Electronic Resource
    Electronic Resource
    High flow addition curing polyimides (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1341-1350 
    Details
    ISSN: 0887-624X
    Keywords: addition polyimides ; biphenyldiamine ; benzidine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new series of high flow PMR-type addition curing polyimides was developed, which employed the substitution of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (BTDB) for p-phenylenediamine (p-PDA) in a PMR-II formulation. These thermoset polyimides, designated as 12F resins, were prepared from BTDB and the dimethyl ester of 4,4′-(hexafluoroisopropylidene)-diphthalic acid (HFDE) with either nadic ester (NE) or p-aminostyrene (PAS) as the endcaps for addition curing. The 12F prepolymers displayed lower melting temperatures in DSC analysis, and higher melt flow in rheological studies than the corresponding PMR-II polyimides. Long-term isothermal aging studies showed that BTDB-based 12F resins exhibited comparable thermo-oxidative stability to p-PDA based PMR-II polyimides. The noncoplanar 2- and 2′-disubstituted biphenyldiamine (BTDB) not only lowered the melt viscosities of 12F prepolymers, but also retained reasonable thermal stability of the cured resins. The 12F polyimide resin with p-aminostyrene endcaps showed the best promise for long-term, high-temperature application at 343°C (650°F). © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320715
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Synthesis and Characterization of Polyimides with Ether Linkages (1998)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A series of polyimides derived from a newly synthesized diamine, namely, 4,4-bis(4-aminophenoxy)-2,2-dimethylbiphenyl (BAPD), were developed and characterized. Their physical and thermal properties were compared to polyimides based on'commercially available 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP).
    Keywords: Nonmetallic Materials
    Format: application/pdf
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  • 3
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    Low-Cost, High Glass-Transition Temperature, Thermosetting Polyimide Developed (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: PMR-15 polyimide, developed in the mid-1970's at the NASA Lewis Research Center, is recognized as a state-of-the-art high-temperature resin for composite applications in the temperature range of 500 to 550 F (260 to 288 C). PMR-15 offers easy processing and good property retention at a reasonable cost. For these reasons, it is widely used in both military and commercial aircraft engine components. Traditionally, polyimide composites have been designed for long-term use at 500 to 600 F over thousands of hours. However, new applications in reusable launch vehicles (RLV's) require lightweight materials that can perform for short times (tens of hours) at temperatures between 800 and 1000 F (425 and 538 C). Current efforts at Lewis are focused on raising the use temperature of polyimide composites by increasing the glass-transition temperature of the matrix resins. Achieving this dramatic increase in the upper use temperature without sacrificing polymer and composite processability is a major technical challenge.
    Keywords: Composite Materials
    Type: Research and Technology 1998; NASA/TM-1999-208815
    Format: application/pdf
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  • 4
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    High T(sub g) Polymides for Resin Transfer Molding (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: A series of new polyimide resins with low melt viscosities and high glass transition temperatures (T(sub g)'s) of 340-350 C were developed for resin transfer molding (RTM) applications. The viscosities of these polyimide resins, based on 2,3,3'4'-Biphenyltetracarboxylic Dianhydride (a-BPDA), are in the range of 10-30 poise. The composites were fabricated successfully at 260-280 C with a pot life of 30-60 minutes by the RTM process. The viscosity profiles of the polyimide resins and the mechanical properties of the polyimide carbon fiber composites will be discussed.
    Keywords: Nonmetallic Materials
    Type: ISSE 2005 Symposium and Exhibition; 1-5 May 20055; Long Beach, CA; United States
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  • 5
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    Evaluation of RTM370 Polyimide Composites by Resin Film Infusion (RFI) (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: RTM370 imide oligomer based on 2,3,3',4'-biphenyl dianhydride (a-BPDA), 3,4'-oxydianiline (3,4'-ODA) and terminated with the 4-phenylethynylphthalic (PEPA) endcap has been shown to exhibit a low melt viscosity (10-30 poise) at 280 C with a pot-life of 1-2 h and a high cured glass-transition temperature (Tg) of 370 C. RTM370 resin has been successfully infused into fiberglass-stitched T650-35 carbon-fabric preforms (ranged from 3- to 6-mm thick) by resin film infusion (RFI). The resulting composite panels were inspected by ultrasonic C-scan and by photomicrographs before and after post-curing as a quality control. Mechanical tests such as unnotched compression (UNC), open-hole compression (OHC), and short-beam shear strength (SBS) at ambient and elevated temperatures were performed before and after isothermal aging at 288 C for 1000 h to assess high-temperature performance. Thermal cycling of RTM370 stitched composites was also conducted from -54 C to 288 C for up to 1600 cycles to evaluate the microcrack resistance of RTM370 polyimide composites fabricated by RFI.
    Keywords: Composite Materials
    Type: GRC-E-DAA-TN11847 , SAMPE Technical Conference 2014; Jun 02, 2014 - Jun 05, 2014; Seattle, WA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Additive Manufacturing of Ultem Polymers and Composites (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimdes Ultem 9085 and experimental Ultem 1000 filled with 10 chopped carbon fiber. A property comparison between FDM-printed and injection molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25-31. Coupons of Ultem 9085, experimental Ultem 1000 composites and XH6050 resin were tested at room temperature and 400F to evaluate their corresponding mechanical properties.
    Keywords: Mechanical Engineering; Composite Materials
    Type: GRC-E-DAA-TN26595 , The Composites and Advanced Materials Expo CAMX; Oct 26, 2015 - Oct 29, 2015; Dallas, TX; United States
    Format: application/pdf
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  • 7
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    Polyimide Composites Based on Asymmetric Dianhydrides (a-ODPA vs a-BPDA) (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: RTM Resins based on a-ODPA and a-BPDA with kinked diamines exhibit low-melt viscosity (approximately 10 poise). Composites made from a-ODPA resins (T(sub g) = 265-330 C) by RTM display good mechanical properties at 288 C (550 F), but soften at 315 C (600 F). Composites of RTM370 based on a-BPDA retain excellent mechanical properties at 315 C, exceeding BMI-5270-1 capability.
    Keywords: Composite Materials
    Type: International SAMPE Symposium and Exhibition; May 18, 2009 - May 21, 2009; Baltimore, MD; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    A Fully Nonmetallic Gas Turbine Engine Enabled by Additive Manufacturing, Part II: Additive Manufacturing and Characterization of Polymer Composites (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This publication is the second part of the three part report of the project entitled "A Fully Nonmetallic Gas Turbine Engine Enabled by Additive Manufacturing" funded by NASA Aeronautics Research Institute (NARI). The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimides-Ultem 9085 and experimental Ultem 1000 mixed with 10% chopped carbon fiber. A property comparison between FDM-printed and injection molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25 to 31%. Coupons of Ultem 9085, experimental Ultem 1000 composites and XH6050 resin were tested at room temperature and 400F to evaluate their corresponding mechanical properties. A preliminary modeling was also initiated to predict the mechanical properties of FDM-printed Ultem 9085 coupons in relation to varied raster angles and void contents, using the GRC-developed MAC/GMC program.
    Keywords: Instrumentation and Photography; Nonmetallic Materials
    Type: NASA/TM-2015-218749 , E-19075 , GRC-E-DAA-TN21324
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Composite Properties of RTM370 Polyimide Fabricated by Vacuum Assisted Resin Transfer Molding (VARTM) (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: RTM370 imide resin based on 2,3,3?,4?-biphenyl dianhydride (a-BPDA), 3,4'-oxydianinline (3,4'-ODA) with the 4-phenylethynylphthalic (PEPA) endcap has been shown to exhibit a high cured T(sub g) (370 C) and low melt viscosity (10-30 poise) at 280 C with a pot-life of 1-2 h. Previously, RTM370 resin has been successfully fabricated into composites reinforced with T650-35 carbon fabrics by resin transfer molding (RTM). RTM370 composites exhibit excellent mechanical properties up to 327?C (620?F), and outstanding property retention after aging at 288?C (550?F) for 1000 h. In this work, RTM370 composites were fabricated by vacuum assisted resin transfer molding (VARTM), using vacuum bags on a steel plate. The mechanical properties of RTM370 composites fabricated by VARTM are compared to those prepared by RTM.
    Keywords: Composite Materials
    Type: E-18061 , Society for Advancement of Materials and Process Engineering (SAMPE); Fort Worth, TX; United States
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    NASA TECHNICAL REPORTS
  • 10
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    Effects of Endcaps on the Properties of Polyimide/Carbon Fiber Composites (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-10
    Description: Carbon fiber (T650-35) composites were fabricated from polyimide resins, using 4,4'-(hexafluoroisopropylidene) diphthalic acid, dimethyl esters (HFDE) and p-phenylenediamine (p-PDA) with three different endcaps; namely, nadic ester (NE), p-aminostyrene (p-AS) and 4-phenylethynylphthalic acid, methyl ester. The curing chemistry of these endcaps will be reviewed. The thermo-oxidative stability as well as the physical and mechanical properties of these polyimide/carbon fiber composites will be discussed.
    Keywords: Composite Materials
    Type: E-9351 , ; 1113-1123
    Format: text
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