The effects of exposure in space on two high-performance polymers

Films of a polyimide, poly(pyromellitimide-1,4-diphenyl ether), and a poly(etherimide), commercial Ultem®, both pure and with additives were exposed to the low earth orbit (LEO) space environment on several missions of the Materials on the International Space Station Experiment (MISSE). The additives, which contained aluminum or boron, were designed to interact with atomic oxygen to form a protective metal oxide coating. A polyimide film containing 10% aluminum acetylacetonate (Al(acac)3) survived an exposure of nearly four year while an adjacent pure film was completely eroded.After exposure in space, films containing aluminum showed an enhanced amount of the element on the surface along with an enhanced amount of oxygen. Boron-containing films showed no enhancement of the element after exposure. The temperature of 10% mass loss increased with space exposure for films containing aluminum but decreased for those containing boron. The glass transition temperature (Tg) increased after space exposure for polyimide films containing Al(acac)3.