LDEF polymeric materials: 10 months versus 5.8 years of exposure

The chemical characterization of several polymeric materials which received 10 months of exposure and 5.8 years of exposure on a Row 9 Long Duration Exposure Facility (LDEF) experiment (A0134) is reported. Specimens include fluorinated ethylene propylene (FEP) teflon film, polysulfone film, and graphite fiber reinforced epoxy amd polysulfone matrix composites. The responses of these materials to the two LEO exposures are compared. The results of infrared, thermal, x-ray photoelectron, and scanning electron microscope analyses are reported. Solution property measurements of various molecular weight parameters are presented for the thermoplastic polysulfone materials. Molecular level effects attributable to exposure that were present in 10-month exposed specimens were not found in 5.8-year exposed specimens. This result suggests that increased atomic oxygen fluence toward the end of the LDEF mission may have eroded away selected environmentally induced changes in surface chemistry for 5.8-year exposure specimens.