Numerical investigation of radiation shielding properties of polyethylene-based nanocomposite materials in different space environments

Human space missions beyond near Earth orbit require mitigating risk factors associated with radiation exposure. Current materials show many limitations in this regard and their applications in crew exploration vehicles, spacesuits and human habitats need further technological advancement. At the moment, polyethylene layers offer the most effective protection against high-energy charged particles in space, yet this material is mainly used in non-structural applications due to its poor mechanical properties. Doping polyethylene matrix with nanoparticles, such as carbon nanotubes and graphene, can significantly enhance the mechanical, electrical and thermal properties of this polymer. However, the effects of carbon nanoparticles on the nanocomposite radiation shielding performance in space are rather unknown. In this study, we numerically investigate the radiation properties of polyethylene-based nanocomposites for space protection using the HZETRN2015 code by NASA. In particular, we analyze the role of single-walled carbon nanotubes (SWCNT) and graphene oxide (GO) nanoplatelets, at different loadings, on the equivalent dose absorbed by the nanocomposites in various radiation fields in space. The choice of polyethylene as the optimal matrix for radiation shielding was confirmed by preliminary studies on different aerospace-grade polymers, aluminium and liquid hydrogen. Simulations were performed for the case of galactic cosmic rays, solar particles events, and for the LEO radiation environment. Composites made of polyethylene and boron carbide particles were also analyzed for comparison with the carbon-filled composites. Results from simulations show that the shielding properties are comparable to the neat polyethylene at low loadings (1-5 wt%) of filler, with the GO nanoplatelets being the best reinforcement for space radiation protection among the investigated fillers.