Comparison of damage mechanism of polyimide films in space radiation environments

Abstract Thin polyimide (PI) film are widely used as structure material or functional material of spacecraft, but their microstructure and properties may be damaged by space radiation environments such as electron, proton, and ultraviolet and so on By using space combined radiation simulation facility and X ray photoelectron spectroscopy (XPS), the damage mechanism of PI film in different irradiation environments were studied. Both charged particles and ultraviolet photons cause the breakage and cross linking of molecular bonds of PI films. Among them, the charged particles mainly show that the PI film breaks the molecular valence bond, while the ultraviolet photon mainly shows the cross linking of the molecular valence bond. For charged particles, the breakage of PMDA molecular chain, especially the break of C = O double bond and -N (CO) bond is the main effect, and at the same time, C-O is generated. For UV irradiation, the breakage of C = O bond, C-O bond, C-N bond and C-C bond mainly occurred firstly, and then the cross-linking between ions of C, N, O with the benzene ring and between different benzene rings will appears with the UV irradiation.