Enhanced thermal and electrical insulation properties of polyimide films determined via a two-dimensional layered double hydroxide–potassium perfluorooctane sulfonate material

Polyimide (PI) films used in aerospace and rail applications are degraded by thermal, chemical, and electric power under the effect of insulation aging. To prevent these types of degradation, we prepared nanocomposite films of PI and layered double hydroxide (LDH) modified with the potassium perfluorooctane sulfonate (FS) by an in situ method. On the whole, the glass-transition temperature, dielectric constant (ɛ′), and corona-resistance lifetime of the nanocomposite films increased over those of the pure PI film, but the temperature at 10 wt % weight loss, breakdown strength, and volume resistance decreased correspondingly as a whole. The PI matrix was protected by the inorganic material of LDH–FS with a high ɛ′ from corona corrosion. Furthermore, the heat and chemical interactions of the composite films improved the corona-resistance lifetime, despite the decrease in the breakdown strength; this should result in promising applications for insulation parts of variable-frequency motors.