Effect of polybenzimidazole (PBI) film coating on hypervelocity impact resistance for space applications

Abstract

The use of lightweight polymeric composites with better physical and multifunctional capabilities in spacecraft can reduce its operating cost. However, the conventional carbon epoxy composites(CFRP) that are employed in the space environment, mostly Low Earth Orbit(LEO), have very poor shielding performance to environmental factors like Atomic Oxygen(AO), Ultraviolet radiation(UV), high vacuum, Thermal cycling and space debris impacts. Therefore, a polymer coating using Polybenzimidazole(PBI), a high performance thermoplastic polymer, is suggested in this research as a method to improve the shielding performance towards hypervelocity debris impact. The coated samples tested for resistance to AO, UV, thermal cycling and high vacuum in a LEO simulation facility revealed that the mass loss and surface erosion decreases, inferring enhanced protection than CFRP. Hypervelocity impact tests performed using a two stage light gas gun(LGG) showed that the energy absorption of the CFRP improved by PBI coating. Therefore, the PBI film coating can effectively improve the shielding performance of the composite material. The study also discusses the effectiveness of adding nanomaterials like carbon nanotubes(CNT’s) and graphene in the PBI coating towards the LEO environment shielding performance. It was observed that adding CNT’s and graphene had no considerable improvement in impact energy absorption. Regardless of this, both nanoparticles showed a very good reduction in mass loss and surface erosion towards other LEO environmental factors making them suitable as fillers in the PBI film.