Study of the properties and structure of fluoropolymer films after space exposure on the Mir space station

Exposure in low Earth orbits (LEO) leads to alteration in properties of both outer and inner (screened) fluoropolymer films F4-MB and FEP-100A. Space environment factors have an effect primarily on the open surface of outer films. The volume and mass of the FEP-100A films accessible to the direct impact of space environment factors underwent nonequivalent changes, indicating an increase in the average density of the polymer. The surface of these films showed contact-angle anisotropy, thereby indicating the formation of spatially oriented structures on the surface. The study of the surface properties of the films revealed that the surface tension and the work of adhesion increased and both outer and (to a lesser extent) inner films became more hydrophilic after exposure. The hydrophilization process prevalently occurred during the first 28 months of exposure in LEO.