Polyimide Used in Space Applications

Polyimide (PI) is an interesting material for space applications as it offers excellent thermal properties. However, due to its dielectric properties, charge storage and release can be at the origin of electrostatic discharges that are hazardous for the surrounding electrical equipment. Depending on the spacecraft orbit, it is necessary to study the impact of specific surrounding environment. In any cases, the effect of vacuum and temperature variations can be combined with electrons and protons’ irradiation, atomic oxygen erosion, and photons impact from UV exposure. On the market, there exist many types of PI, and since several years, composite are also developed. The main properties that are usually observed are the conductivity that is analyzed from surface potential decay, the photoemission and the ability to initiate and propagate surface flashover. Since several years, the space charge storage analysis by the pulse electro-acoustic method has been developed as an interesting complementary tool. It is important to remember that experimental characterization needs to be representative to the space environment especially because it has been observed that PI can recover its original properties in air in a couple of hours depending on the ageing degree.