SURFACE-STRUCTURE AND PROPERTIES OF POLYMERS IRRADIATED WITH HYPERTHERMAL ATOMIC OXYGEN

Surface properties of Kapton (R) were analysed after different exposures to ground state fast atomic oxygen (FAG) and vacuum ultraviolet radiation in the atomic oxygen beam facility at the University of Toronto Institute for Aerospace Studies. X-ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements were used to characterize the chemical and physical changes to the surfaces of the materials analysed. The most important changes in the surface chemistry of Kapton induced by the various exposures to FAO were oxidative degradation of the polymer and substantial changes in supermolecular organization and morphology of the surface layer. A very weak adhesion of the rough top layer to the original Kapton has been observed after an atomic oxygen irradiation with a total fluence of 1.3 x 10(21) atoms cm(-2), which is comparable to some low earth orbit (LEG) exposures. Comparison was made between pristine samples and the cleaned surface of samples that had been exposed in the atomic oxygen beam facility and in the LEO environment. An ageing effect was observed in the surface layer of exposed samples after a prolonged storage. For several polymer materials, a correlation was found between the erosion yield when exposed to FAO and the dispersion component of the surface tension of the pristine material.