The effects of atomic oxygen and ion irradiation degradation on multi- polymers: A combined ground-based exposure and ReaxFF-MD simulation

YF Zhang and H Yuan and WQ Yan and ZQ Zhang and SN Chen and B Liao and X Ouyang and L Chen and X Zhang, POLYMER DEGRADATION AND STABILITY, 205, 110134 (2022).

DOI: 10.1016/j.polymdegradstab.2022.110134

Polymers are ubiquitous in the aerospace industry, and their atomic oxygen (AO) exposure and ion irradiation stability are a chief concern. In this work, the AO and ion-irradiation degradation mechanisms for Mylar, Teonex, Vectra, Kapton and Teflon were investigated by adopting ground-based simulated environments (AO exposure and Fe+ irradiation tests) and reactive molecular dynamics (ReaxFF-MD) simulations. Mylar, Teonex, Vectra and Kapton show analogous AO degradation mechanisms, which are associated with the fracture and oxidation of the molecular chain skeleton and the emission of volatile small molecular species, resulting in mass loss. Teflon exhibits distinctive AO erosion kinetics, and the existence of an overall drift of the macromolecular chain with AO emission greatly compromises its stability. Moreover, Mylar, Teonex, Vectra and Kapton also exhibit comparable irradiation damage mechanisms and radical evolution. The elimination of C=O, C-O-C and C-N (only for Kapton) bonds and the generation of phenyl, phenoxyl and ketone radicals are the primary consequences of Fe+ irradiation. However, only subtle C-F bond breakage for Teflon can be detected during Fe+ irradiation, and the corresponding peroxide radicals are formed after contact with air atmosphere.

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