Molecular-Level Response of Selected Polymeric Materials to the Low Earth Orbit Environment

Abstract

The NASA Long Duration Exposure Facility (LDEF) enabled the exposure of a wide variety of materials to the low Earth orbit (LEO) environment. This paper provides a summary of research conducted at the Langley Research Center into the response of selected LDEF polymers to this environment. Materials examined include graphite fiber reinforced epoxy, polysulfone, and addition polyimide matrix composites, films of FEP Teflon, Kapton, and several experimental high performance polyimides, and films of more traditional polymers such as poly(vinyl toluene) and polystyrene. Exposure duration was either 10 months or 5.8 years.Flight and control specimens were characterized by a number of analytical techniques including ultraviolet-visible and infrared spectroscopy, thermal analysis, scanning electron and scanning tunneling microscopy, x-ray photoelectron spectroscopy, and, in some instances, selected solution property measurements. Characterized effects were found to be primarily surface phenomena. These effects included atomic oxygen-induced erosion of unprotected surfaces and ultraviolet-induced discoloration and changes in selected molecular level parameters. No gross changes in molecular structure or glass transition temperature were noted.The National Aeronautics and Space Administration Long Duration Exposure Facility (LDEF) provided a novel opportunity for the aerospace community to examine the effects of long term low Earth orbit (LEO) exposure on a variety of materials. The 11-ton satellite depicted in Figure 1 was returned to Earth by the Space Shuttle Columbia in January 1990 after 69 months in orbit. It contained 57 experiments to assess the effects of the space environment on materials, living matter, and various space systems (1). The saga of this remarkable vehicle is continuing to unfold through a series of symposia, workshops, and journal articles (2-7). Perhaps as much as 90% of our first-hand knowledge of LEO space environmental effects rests with the LDEF and its contents (8).

Synthesis and characterization of rubbery highly fluorinated siloxane-imide segmented copolymers

“…During the last ten years, the synthesis of copolymers combining aromatic imide and siloxane blocks in their main chain has been the target of several research groups, working either in the field of new high‐performances polymers for aerospace applications and advanced microelectronics, or in the field of membrane separations . Indeed, the block copolymer strategy is a very useful one for creating new materials based on thermodynamically incompatible moieties.…”

Effect of γ-irradiation on the structure of activated carbons produced from Turkish Elbistan lignite

“…doi:10. 1016/j.radphyschem.2004.09.025 in space vehicles (Young and Slemp, 1990;Young et al, 1994). The radiolysis of active carbons with g-rays is not an extensively studied topic.…”

Selection and Optimization of Piezoelectric Polyvinylidene Fluoride Polymers for Adaptive Optics in Space Environments

“…Mechanical properties will suffer with various types of radiation (vacuum UV, 1 -, X-ray, charged particles) and extreme temperature fluctuations. Experiments carried out on the low earth orbit (LEO) long-duration exposure facility (LDEF) in the late 1980s [2][3][4] and NASA's experience with material selection for both satellite and space station applications, as well as performance feedback from the Hubble space telescope (HST) [5][6][7] have revealed considerable polymer weaknesses in these environments. While the radiation degradation of polymers is an established field [8] there is little information available on the performance of specialized features such as the piezoelectric and/or similar properties of PVDF with respect to their expected changes upon LEO exposure.…”