Degradation of polymers by hyperthermal atomic oxygen

Degradation of polymers by hyperthermal species (e.g. atomic oxygen (ATOX)) occurs in a variety of practical systems including external surfaces of spacecraft in low earth orbits (LEO), for which the impact with the residual atomic oxygen (impact energy 3–7 eV) results in significant erosion. In the present work the effects of hyperthermal species on two polymers commonly used for space applications (Kapton H and Teflon FEP) were investigated. The polymers were exposed to 30 eV O⁺ and Ne⁺ fluences of 10¹⁵–10¹⁹ ions cm⁻². The phenomena investigated included total mass loss and changes of surface morphology (SEM and AFM) and surface chemical composition (XPS). The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of O⁺ and Ne⁺ bombardment. AFM analysis was found very powerful in studying the damage from its initial atomic scale (roughness of ∼ 1 nm) to its final macroscopic scale (roughness > 1 μm).