Preparation and atomic oxygen resistance of hybrid polyimide

Atomic oxygen (AO), the predominant components and the most active species in low earth orbit atmosphere, can cause the erosion and degradation of spacecraft materials. To improve the AO-resistance of the resin, Tetraethyl orthosilicate (TEOS) was added into the polyimide (PI) matrix, and then the inorganic phases of SiO₂ were generated in-situ using sol-gel method and the SiO₂/PI hybrid materials were obtained. The ground-based simulation experiments were carried out to evaluate the AO-resistance of the SiO₂/PI hybrid materials. The mass, surface morphology and surface composition of the samples were compared before and after the AO experiments. The effects of the adding amount of TEOS and the improving mechanism of the AO-resistance were analyzed. Results show that the AO-resistance of hybrid materials is better than that of the pristine resin and the relative mass loss is 31.6%~14.8%. There are two essential reasons of the AO-resistance of the hybrid material that the silicones and silica are generated in the resin matrix during sol-gel process and the silica protective coating is formed on the sample surface in AO environment.