Publication

Abstract : This chapter describes basic understanding of high-energy radiation as well as space vacuum and properties of high-performance polymers and adhesives when exposed to high-energy radiation in vacuum. Therefore, different radiation conditions are analyzed, and stability of different polymers under radiation and vacuum are described. As a case study, performance of space durable polymer such as polybenzimidazole (PBI) modified by low-pressure plasma and atmospheric-pressure plasma and fabrication of the polymer by ultrahigh temperature-resistant epoxy adhesive (DURALCO 4703) is reported. The service temperature of this particular adhesive ranges from −260°C to +350°C, and in addition this adhesive has excellent resistance to most acids, alkalis, solvents, corrosive agents, radiation, and fire, making it extremely useful when subject to space radiation. Prior to fabrication of PBI, the surface of PBI is ultrasonically cleaned by acetone followed by its modification through low-pressure plasma with 30, 60, 120, 240, and 480 s of exposure. Surface characterization of the unmodified and modified PBI sheets is carried out by contact-angle measurements by which surface energy is calculated. It is observed that polar component of surface energy leading to total surface energy of the polymer increases significantly when exposed to low-pressure plasma. X-ray Photoelectron Spectroscopy (XPS) reveals that the polymer surface becomes hydrophilic, resulting in increase in surface energy. High-energy radiation related to outer space is simulated with mixed-field radiation generated by SLOWPOKE-2 (safe low power critical experiment) nuclear reactor. Therefore, in order to see the performance of the adhesive joint of PBI under outer-space radiation, the joint is exposed to SLOWPOKE-2 nuclear reactor up to a dose of 444 kGy and critically analyzed.