聚酰亚胺（PI）薄膜广泛用于航天器热控多层和大型展开结构中，但在空间紫外辐射环境下，其力学性能会发生退化。在近紫外和远紫外辐射环境下，对均苯型PI薄膜力学性能退化规律及退化机理进行研究。研究发现：在辐照初期，近紫外辐射和远紫外辐射均可造成均苯型PI薄膜抗拉强度和断裂伸长率下降，但远紫外辐射下降更加明显；随着曝辐量的增加，PI薄膜的抗拉强度和断裂伸长率均呈指数规律增长，而后趋于稳定，近紫外辐照后薄膜材料的力学性能优于远紫外辐照后薄膜材料的力学性能；断裂和交联是造成薄膜材料力学性能退化的主要原因，在紫外辐照初期以断裂为主，随着曝辐量的增加，以交联为主。%Polyimide film was widely used in multilayered insulation and deployable structures of spacecraft,while their mechanical properties can be damaged by space ultraviolet irradiation. The mechanical property and mechanism of polyimide film in near ultraviolet and far ultraviolet radiation was studied and following results can be obtained:with the increasing of near ultraviolet or far ultraviolet irradiation,the rupture elongation and tensile strength of polyimide decrease firstly and then exponentially increase then tend to stable. In the early stage,the decrease of mechanical properties of poly-imide films in near ultraviolet is faster than in far ultraviolet irradiation. And the mechanical properties of polyimide films irradiated by long duration near ultraviolet are better than in far ultraviolet environment. The breakage and cross linkage of molecular bond is the major cause of change of polyimide’ s mechanical property in ultraviolet environments,and break-age is the major origin in early stage of irradiation and cross linkage is for the increase of mechanical property in subse-quent ultraviolet irradiation.
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