Radiation-induced effects on the mechanical properties of Kapton H type polyimide films of different thicknesses

The mechanical characteristics of polyimide films of the Kapton H type with different thicknesses, both in the initial state and after irradiation separately with corpuscular radiation fluxes from the Earth’s radiation belts (protons or electrons) and electromagnetic radiation from the transatmospheric Sun in the range of vacuum ultraviolet and ultrasoft X-rays, simulated in the laboratory, were investigated. The preservation of the forced elastic state in the irradiated films was revealed. The influence of corpuscular and electromagnetic irradiation on several characteristics (forced elasticity limit, rupture stress, deformation to rupture) is different, and these parameters vary in opposite ways with thickness. After exposure to all types of irradiation, a redistribution of the contributions (reversible deformation upon load removal and delayed forced elastic deformation, as well as irreversible deformation) to the total deformation before rupture was observed. The nature and magnitude of this redistribution also depend on the type of irradiation and the film thickness. The elastic moduli, including Young’s modulus and the modulus at the final stage of forced elasticity, with the exception of the modulus of proton-irradiated films, increase after all types of irradiation.