A study on polyimide MLI of the ten months flown space flyer unit

The 10-months low Earth orbit (LEG) flight and subsequent January 1996 return to Earth of the first Japan space environment utilization, the Space Flyer Unit (SFU) provided an opportunity for us to examine the effects of space exposure on various materials of the SFU. Aromatic polyimide multilayer insulation blanket (MLI) was one of major polymeric material, covering the outer surfaces of the SFU. By visual inspection of the SFU returned, it was observed that most of surfaces of polyimide MLI lost their golden shining color and became opaque with signs of contamination and degradation. For understanding the 10-month Eight of the SFU in LEG, the night and control polyimide MLI specimens were characterized by chemical, physical and thermomechanical techniques including visible and infrared spectroscopy(FT/IR), thermal analysis(TG,DSC), scanning electron microscopy(SEM), x-ray photoelectron spectroscopy(XPS,ESCA) and optical properties measurements. Preliminary results exhibited that characterized effects were found to be primarily surface phenomena, indicating the heavy contamination of silicon derivatives. ?he exposed surfaces projecting into space were changed to the rugged by synergistic effects. Although the surfaces of exposed polyimide MLIs showed typical of the ''Christmas tree'' morphology as previously reported, the decreases in thickness in these outer layers were only less than 2 mu m, suggesting the protection effect by silicon-containing contaminant against atomic oxygen.