The effect of low Earth orbit atomic oxygen exposure on phenylphosphine oxide-containing polymers

Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle Eight (STS-85) as part of Right experim ent designated Evaluation of Space Environment and Effects on Materials (ES EM). This flight experiment was a cooperative effort between the NASA Langl ey Research Center (LaRC) and the National Space Development Agency of Japa n (NASDA). The thin-film samples described herein were part of an atomic ox ygen exposure (AOE) experiment and were exposed to primarily atomic oxygen (similar to 1 x 10(19) atoms cm(-2)). The thin-film samples consisted of th ree phosphine oxide-containing polymers (arylene ether, benzimidazole and i mide). Based on post-flight analyses using atomic force microscopy, x-ray p hoto-electron spectroscopy and weight loss data, it was found that the expo sure of these materials to atomic oxygen (AO) produces a phosphorus oxide l ayer on the surface of the samples. Earlier work has shown that this layer provides a barrier towards further attack by AO. Consequently, these materi als do not exhibit linear erosion rates which is in contrast with most orga nic polymers. Qualitatively, the results obtained from these analyses compa re favourably with those obtained from samples exposed to AO and/or an oxyg en plasma in ground-based exposure experiments. The results of the low Eart h orbit AO exposure on these materials will be compared with those of groun d-based exposure to AO.