Fluorinated PEEK and XLPE as Promising Insulation Candidates for the Propulsion System of All-Electric Aircraft

This article investigates the surface electrical properties of polyether-ether-ketone (PEEK) and cross-linked polyethylene (XLPE) before and after the fluorination modification. The samples are tested for surface conductivity, surface morphology, and surface antiaging characteristics. The samples are also tested for flashover voltage with ramping voltage under 100, 20, and 10 kPa. The results showed that the surfaces of PEEK and XLPE become slightly smoother with the increase in the fluorination time and the conductivity increased with the increase in the fluorination time. After fluorination, the surface of PEEK shows significant hydrophilicity, while the surface hydrophobicity of XLPE is slightly reduced, and there is a trend of recovery with the extension of the fluorination time. After fluorination, the surface antiaging performance is significantly improved. Compared with the untreated samples, the fluorinated PEEK has a higher flashover voltage at 100 kPa, and the flashover voltage is slightly increased at 10 and 20 kPa, while the flashover voltage of XLPE after fluorination shows a downward trend, especially under low pressures. This study provides a reference for fluorinated polymers as promising candidates for the insulation systems for all-electric aircraft.