Study of the properties and structure of polyimide and bilayer fluoropolyimide films after space exposure on the Mir space station

摘要

Results of examination of bilayer polyimide and fluorinated polyimide films after their exposure to outer space on the Mir space station are reported. The polyimide films were screened by quartz plates during exposure. An increase in the surface energy and the work of adhesion indicate substantial hydrophilization of the open surface, as well as slight hydrophilization of the screened film surface. A difference in values of the surface energy and work of adhesion depending on the orientation of a sample relative to the direction of motion of the space station indicates that the surface properties of the outer surface of the unscreened film became anisotropic in character, with the anisotropy axis being aligned with the direction of motion of the spacecraft. The fact that the outer surface of the film has acquired anisotropic properties is corroborated by the results of study of scanning electron microscopic images and polar plots of brightness. The hydrophilization of the films indicates an increase in the concentration of polar groups. In the space environment, the degradation of the fluoropolymer surface layer and its removal under high-vacuum conditions take place. For the quartz-shielded polyimide films, the surface energy and the work of adhesion remained practically the same as for the unexposed films. It was concluded that solar radiation (mu > 200 nm) does not cause a significant decline in the properties of the polyimide film.