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  • 1
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    Environmental stability graphite/PMR-15 composites (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: During the past few years the Boeing Company was screening graphite composites for use in hot areas of engine nacelle structure. Structural and thermal analyses have shown that there is the potential for a 25 to 30 percent weight savings by using a graphite polyimide (Gr/PI) composite material in this type of structure. Work conducted on the NASA CASTS program (Composites for Advanced Space Transportation Systems) amply demonstrated the capability of Graphite/PMR-15 for short term service (125 hours) at temperatures up to 589 K (600 F). In addition, the CASTS program demonstrated that large structures could be fabricated using Gr/PMR-15. In commercial applications, however, the requirement exists for long term service capability (tens of thousands of hours) at temperatures ranging upwards from 449 K (350 F). The results of Graphite/PMR-15 materials characterization efforts conducted at Boeing are presented with emphasis on materials properties after isothermal aging at temperatures of 449 K (350 F) and above.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Lewis Research Center High Temp. Polymer Matrix Composites; p 329-334
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Characterization of PMR polyimide resin and prepreg (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Procedures for the chemical characterization of PMR-15 resin solutions and graphite-reinforced prepregs were developed, and a chemical data base was established. In addition, a basic understanding of PMR-15 resin chemistry was gained; this was translated into effective processing procedures for the production of high quality graphite composites. During the program the PMR monomers and selected model compounds representative of postulated PMR-15 solution chemistry were acquired and characterized. Based on these data, a baseline PMR-15 resin was formulated and evaluated for processing characteristics and composite properties. Commercially available PMR-15 resins were then obtained and chemically characterized. Composite panels were fabricated and evaluated.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-168217 , NAS 1.26:168217 , D180-26031-2
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Fillers for improved graphite fiber retention by polymer matrix composites (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The results of a program designed to determine the extent to which elemental boron and boron containing fillers added to the matrix resin of graphite/epoxy composites prevent the release of graphite fibers when the composites are exposed to fire and impact conditions are described. The fillers evaluated were boron, boron carbide and aluminum boride. The conditions evaluated were laboratory simulations of those that could exist in the event of an aircraft crash and burn situation. The baseline (i.e., unfilled) laminates evaluated were prepared from commercially available graphite/epoxy. The baseline and filled laminates' mechanical properties, before and after isothermal and humidity aging, also were compared. It was found that a small amount of graphite fiber was released from the baseline graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that the addition of boron and boron containing fillers to the resin matrix eliminated this fiber release. Mechanical properties of laminates containing the boron and boron containing fillers were lower than those of the baseline laminates. These property degradations for two systems: boron (5 micron) at 2.5 percent filler loading, and boron (5 micron) at 5.0 percent filler loading do not appear severe enough to preclude their use in structural composite applications.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-165437
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Quality control developments for graphite/PMR15 polyimide composites materials (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The problem of lot-to-lot and within-lot variability of graphite/PMR-15 prepreg was investigated. The PMR-15 chemical characterization data were evaluated along with the processing conditions controlling the manufacture of PMR-15 resin and monomers. Manufacturing procedures were selected to yield a consistently reproducible graphite prepreg that could be processed into acceptable structural elements.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-159182 , D180-20545-2A
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Development and demonstration of manufacturing processes for fabricating graphite/PMR-15 polyimide structural elements (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The processing requirements for graphite/PMR-15 polyimide composites developed to demonstrate the structural integrity of polyimide composite structural elements at temperatures up to 589K (600 F) are described. Major tasks included: quality assurance development; materials and process development; specification verification; flat panel fabrication; stiffened panel fabrication; honeycomb panel fabrication; chopped fiber moldings; and demonstration component fabrication. Materials, processing, and quality assurance documents were prepared from experimentally derived data. Structural elements consisting of flat panels, corrugated stiffeners, I-beams, hat stiffeners, honeycomb panels, and chopped fiber moldings were made and tested. Property data from 219K (-65 F) to 589K (600 F) were obtained. All elements were made in a production environment. The size of each element was sufficient to insure production capability and structural component applicability. Problems associated with adhesive bonding, laminate and structural element analysis, material variability, and test methods were addressed.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Langley Res. Center Graphite(Polyimide Composites; p 61-84
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Weld bonding of titanium with polyimide adhesives (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-132665 , TRW-22902-6027-TU-00
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Manufacturing processes for fabricating graphite/PMR 15 polyimide structural elements (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Investigations were conducted to obtain commercially available graphite/PMR-15 polyimide prepreg, develop an autoclave manufacturing process, and demonstrate the process by manufacturing structural elements. Controls were established on polymer, prepreg, composite fabrication, and quality assurance, Successful material quality control and processes were demonstrated by fabricating major structural elements including flat laminates, hat sections, I beam sections, honeycomb sandwich structures, and molded graphite reinforced fittings. Successful fabrication of structural elements and simulated section of the space shuttle aft body flap shows that the graphite/PMR-15 polyimide system and the developed processes are ready for further evaluation in flight test hardware.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-159129 , D180-20545-2
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Polyimide adhesives for weld-bonding titanium (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system and a new adhesive system, CP/CFA, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219K (-65 F) to 561K (550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of weld-bonding for fabricating stringer stiffened skin panels.
    Keywords: NONMETALLIC MATERIALS
    Type: National Symposium and Exhibition on Bicentennial of materials progress; Apr 06, 1976 - Apr 08, 1976; Los Angeles, CA
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Development of autoclavable addition type polyimides (1974)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two highly promising approaches to yield autoclavable addition-type polyimides were identified and evaluated in the program. Conditions were established for autoclave preparation of Hercules HMS graphite fiber reinforced composites in the temperature range of 473 K to 505 K under an applied pressure of 0.7 MN/m2 (100 psi) for time durations up to four hours. Upon oven postcure in air at 589 K, composite samples demonstrated high mechanical property retention at 561 K after isothermal aging in air for 1000 hours. Promise was shown for shorter term mechanical property retention at 589 K upon exposure in air at this temperature.
    Keywords: MATERIALS, NONMETALLIC
    Type: NASA-CR-121251 , TRW-21863-6013-RU-00
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Fabrication of PDA/HTS prototype components (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A process was developed for autoclave molding structural poly-(Diels-Alder) polyimide (PDA) resin/HTS graphite composites for short-term 600 F service. The autoclave molding process used to fabricate these composites required a maximum cure temperature of 427 K (400 F) and a maximum molding pressure of 0.7 MN/sq m (100 psig). This process then was adapted to the fabrication of co-cured polyimide sandwich panels consisting of PDA/HTS skins, PDA syntactic foam and polyimide/glass honeycomb core. Fabrication ease was demonstrated by manufacturing five three-quarter scale YF-12 wing panels using the PDA resin. It was concluded from successful evaluation of these prototype units that the PDA resin is suitable for fabrication of components using commercial equipment.
    Keywords: MECHANICAL ENGINEERING
    Type: National Technical Conference on Bicentennial of materials; Oct 12, 1976 - Oct 14, 1976; Seattle, WA
    Format: text
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    NASA TECHNICAL REPORTS
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