Degradation of Polymer Materials in Low Earth Orbits

Abstract

The results of study on two batches of polyimide film materials exposed to the space environment for 28 and 42 months at the Mir space station are discussed. The resistance of polymer films to space environment factors depends on the chemical structure and composition of a polymer material, the polyimide films, especially fluorinated and metalized, undergo considerably stronger changes than fluoropolymers. It was found that the rate of degradation of polymer materials is nonlinearly related to the time of exposure to the space environment. The circular brightness plots and contact angles of outer polyimide films are anisotropic in character, the directions of brightness plot axes and the contact angle are determined by the orientation of the film on the panel with respect to the direction of spacecraft motion. Irradiation by solar light at λ ≥ 200 nm did not lead to noticeable degradation of the polymers. It was assumed that the degradation of polymer materials was initiated by bombardment with heavy particles (molecules, atoms, and ions of oxygen, nitrogen, etc.) due to a spacecraft residual atmosphere.