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  • 11
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    Performance of selected polymeric materials on LDEF (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The NASA Long Duration Exposure Facility (LDEF) provided a unique environmental exposure of a wide variety of materials for potential advanced spacecraft application. This paper examines the molecular level response of selected polymeric materials which flew onboard this vehicle. Polymers include epolyimide, polysulfone, and polystyrene film and polyimide, polysulfone, and epoxy matrix resin/graphite fiber reinforced composites. Several promising experimental films were also studied. Most specimens received 5.8 years of low Earth orbital (LEO) exposure on LDEF. Several samples received on 10 months of exposure. Chemical characterization techniques included ultraviolet-visible and infrared spectroscopy, thermal analysis, x-ray photoelectron spectroscopy, and selected solution property measurements. Results suggest that many molecular level effects present during the first 10 months of exposure were not present after 5.8 years of exposure for specimens on or near Row 9. Increased AO fluence near the end of the mission likely eroded away much environmentally induced surface phenomena. The objective of this work is to provide fundamental information for use in improving the performance of polymeric materials for LEO application. A secondary objective is to gain an appreciation for the constraints and limitations of results from LDEF polymeric materials experiments.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Marshall Space Flight Center, LDEF Materials Results for Spacecraft Applications; p 125-142
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 12
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    Effects of LDEF flight exposure on selected polymer matrix resin composite materials (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composites materials which received over five years and nine months of exposure to the low earth orbit (LEO) environment in experiment AO134 on the Long Duration Exposure Facility is reported. The changes in mechanical properties of ultimate tensile strength and tensile modulus for exposed flight specimens are compared to the three sets of control specimens. Marked changes in surface appearance are discussed, and resin loss is reported. The chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymetric matrix had not changed significantly in response to this exposure.
    Keywords: NONMETALLIC MATERIALS
    Type: LDEF: 69 Months in Space. First Post-Retrieval Symposium, Part 2; p 1149-1162
    Format: text
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    NASA TECHNICAL REPORTS
  • 13
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    Surface analysis of anodized aluminum clamps from NASA-LDEF satellite (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: Surface analysis results of selected anodized aluminum clamps containing black (Z306) and white (A276) paints which received nearly six years of Low Earth Orbit (LEO) exposure on the Long Duration Exposure Facility are reported. Surface analytical techniques, including x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy/energy dispersive analysis by x-ray (SEM/EDAX), showed significant differences in the surface composition of these materials depending upon the position on the LDEF. Differences in the surface composition are attributed to varying amounts of atomic oxygen and vacuum ultraviolet radiation (VUV). Silicon containing compounds were the primary contaminant detected on the materials.
    Keywords: METALLIC MATERIALS
    Type: Second LDEF Post-Retrieval Symposium Abstracts; p 90
    Format: text
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    NASA TECHNICAL REPORTS
  • 14
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    Effects of LDEF flight exposure on selected polymer matrix resin composite materials (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: The characterization of selected graphite fiber reinforced epoxy and polysulfone matrix resin composites which received exposure to the LEO environment on the LDEF is reported. The changes in mechanical properties of ultimate tensile strength and tensile modulus for exposed flight specimens are compared to the three sets of control specimens. Marked changes in surface appearance are discussed, and resin loss is reported. The chemical characterization including IR, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure.
    Keywords: COMPOSITE MATERIALS
    Type: First LDEF Post-Retrieval Symposium Abstracts; p 86
    Format: text
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  • 15
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    Effects of LDEF flight exposure on selected polymeric films and thermal control coatings (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: The characterization of polymeric films and thermal control coatings which were exposed for five years and ten months to the low-Earth environment is reported. Changes in solar absorptance, thermal emittance, and transmission are compared to laboratory control specimens. Sputter-deposited metallic coatings are shown to eliminate atomic oxygen erosion of resin matrix composite materials. The effects of long-term atomic oxygen exposure to metallized FEP Teflon film is characterized. Chemical characterization of polymeric films indicates that although surface erosion occurs, the molecular structure of the basic polymeric film has not changed significantly in response to this exposure.
    Keywords: NONMETALLIC MATERIALS
    Type: First LDEF Post-Retrieval Symposium Abstracts; p 67
    Format: text
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  • 16
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    Chemical characterization of selected LDEF polymeric materials (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: Chemical characterization of selected polymeric materials which received exposure on the Long Duration Exposure Facility (LDEF) is reported. The specimens examined include silvered fluorinated ethylene propylene Teflon thermal blanket material, polysulfone, epoxy, polyimide matrix resin/graphite fiber reinforced composites, and several high performance polymer films. These specimens came from numerous LDEF locations, and thus received different environmental exposures. The results to date show no significant change at the molecular level in the polymer that survived exposure. Scanning electron and scanning tunneling microscopes show resin loss and a texturing of some specimens which resulted in a change in optical properties. The potential effect of a silicon-containing molecular contamination on these materials is addressed. The possibility of continued post-exposure degradation of some polymeric films is also proposed.
    Keywords: NONMETALLIC MATERIALS
    Type: First LDEF Post-Retrieval Symposium Abstracts; p 52
    Format: text
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  • 17
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    LDEF thermal control coatings post-flight analysis (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: The optical, physical, and chemical properties of selected spacecraft thermal control coatings, exposed for 10 months and 5.8 years on the leading edge (Row 9) of the LDEF, are reported. The following coatings were used: quartz/silver optical solar reflector; silvered FEP Teflon; S-13GLO, YB-71, and A-276 white paints; black paint; and sputter deposited coatings over graphite-epoxy composite substrates. The solar absorptance, total normal emittance, scanning electron and X-ray photoelectron microscopy, and X-ray diffraction analyses will be compared for the control, the 10 month exposed, and the 5.8 year exposed specimens. Data suggests that the high atomic flux over the last 6 months of the LDEF mission may have influenced the results from from this coatings experiment.
    Keywords: NONMETALLIC MATERIALS
    Type: Second LDEF Post-Retrieval Symposium Abstracts; p 70
    Format: text
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  • 18
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    LDEF polymeric materials: 10 months versus 5.8 years of exposure (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: The chemical characterization of several polymeric materials which received both 10 months and 5.8 years of exposure on a Row 9 experiment (A0134) is reported. Specimens include polysulfone film, polysulfone matrix/graphite-fiber reinforced composites, and coated and uncoated epoxy matrix/graphite fiber reinforced composites. The effect of 10 months of exposure on an experimental silicon-containing polyimide copolymer film is also reported. The results of infrared, thermal, x-ray photoelectron, and scanning electron microscope analyses will be compared for the two exposures. Solution property measurements on the thermoplastic polysulfone resin will also be presented. Molecular level effects attributable to exposure and present in 10-month specimens are not present in 5.8-year specimens. This suggests that increased atomic oxygen fluence toward the end of the mission may have eroded selected environmentally-induced changes in surface chemistry for 5.8-year specimens.
    Keywords: NONMETALLIC MATERIALS
    Type: Second LDEF Post-Retrieval Symposium Abstracts; p 76
    Format: text
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  • 19
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    Surface characterization of selected LDEF tray clamps (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The surface characterization of chromic acid anodized 6061-T6 aluminum alloy tray clamps has shown differences in surface chemistry depending upon the position on the Long Duration Exposure Facility (LDEF). Water contact angle results showed no changes in wettability of the tray clamps. The overall surface topography of the control, trailing edge(E3) and leading edge(D9) samples was similar. The thickness of the aluminum oxide layer for all samples determined by Auger depth profiling was less than one micron. X-ray photoelectron spectroscopy (XPS) analysis of the tray clamps showed significant differences in the surface composition. Carbon and silicon containing compounds were the primary contaminants detected.
    Keywords: METALLIC MATERIALS
    Type: LDEF: 69 Months in Space. Part 3: Second Post-Retrieval Symposium; p 1015-1022
    Format: application/pdf
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  • 20
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    An analysis of LDEF-exposed silvered FEP teflon thermal blanket material (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The characterization of selected silvered fluorinated ethylene propylene (FEP) teflon thermal blanket material which received 5 years and 9 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. X-ray photoelectron spectroscopy, infrared, and thermal analyses did not detect a significant change at the molecular level as the result of this exposure. However, various microscopic analyses revealed a roughening of the coating surface due to atomic oxygen erosion which resulted in some materials changing from specular reflectors of visible radiation to diffuse reflectors. The potential effect of silicon-containing molecular contamination on these materials is addressed.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-104096 , NAS 1.15:104096
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