Flexible solar wings with high energy density, lightweight, small size and large deployment area are one of the first choices for next‐generation spacecraft. However, the flexible solar wings are subjected to irradiation in space and tensile mechanical stress, which produce the charge accumulation effect and result in electrostatic discharge. It is necessary to establish a test method for the conductivity and space charge behaviour of polyimide under tensile stress. The stress–strain characteristics of polyimide under different tensile stresses are studied by the authors. The longitudinal length‐strain characteristics and transverse thickness evolution characteristics under different stresses are also obtained. The results show that the variation of film thickness with tensile force is only about 1% before the yield point. The polyimide films from 50 to 200 μm thick have similar yield and tensile strengths. The ultimate stress of the specimen decreases from approximately 126 to 103 MPa with increasing thickness. The thickness model of polyimide under tensile stress were obtained, which could accurately calculate the voltage amplitude applied on the specimens for measuring the conductivity under different tensile stresses. A basis for investigating the stress–strain characteristics of polyimide films under different tensile stresses are provided, which will facilitate the formulation selection and performance improvement of polyimide for flexible solar wings of spacecraft.

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Photovoltaic (PV) power is one of the most effective green energies, which has attracted extensive attention from the industry and the international community. Polyethylene terephthalate (PET) is the main material of the PV backsheet, providing insulation protection for PV modules. Although PET has excellent optical properties, weather resistance, and chemical resistance, its relatively weak insulation properties restrict its application in engineering plastic. In this paper, the insulating properties of PET/montmorillonite (MMT) are studied. PET/MMT nanocomposites with an MMT content of 1%, 3%, and 5% are prepared by the melt blending method, and their insulating properties are tested. The results show that the addition of MMT can change the distribution of the electric field inside PET, thus, increasing the breakdown voltage. Furthermore, it can reduce the number of times of partial discharge (PD) and weaken the intensity of PD in PET/MMT composites to some extent. When the MMT content is 3%, PET/MMT composites have the best insulation performance. This study can provide a reference for the application of nanocomposites in the field of green energy.