Effect of High-Energy Electron Irradiation on the Microstructure and Properties of Polyetherimide

High-energy electron irradiation is well-known for causing the degradation of the performance of spacecraft materials such as polyetherimide (PEI). In this article, the effect of high-energy electron irradiation on the structure and properties of PEI samples was studied which is produced by linear accelerator. Electron beam energies of 5, 10, 15, and 20 MeV were used. The results show that the carbonyl groups and ether bonds in the internal groups and the molecular chain of PEI are broken by high-energy electron irradiation, resulting in a significant decrease of polarization ability and dielectric constant, from 3.366 to 2.938. Simultaneously, due to the destruction of the symmetry of PEI and the creation of the heterogeneous interfaces inside the PEI, the dielectric loss first decreases and then increases. Besides, the glass transition temperature of irradiated PEI slightly decreases, from 218 °C to 214 °C, and the crystallinity and mechanical properties also decrease. This article provides the experimental basis for the application of PEI in the space-integrated operating environment.