3D printing of radiation shielding polyethylene composites filled with Martian regolith simulant using fused filament fabrication

A highly sought-after objective of Space Agencies is the development of additive manufacturing (AM) technologies and of multifunctional materials, key elements to future exploration and colonization of Moon and Mars. The 3D printing process via fused filament fabrication (FFF) is increasingly viewed as an interesting approach for the in-situ manufacturing of buildings and items using regolith as a feedstock material, enabling the necessary repair and recycling capabilities to ensure crew safety. In this work, we investigate the radiation shielding properties and the FFF 3D printing process of polyethylene-based composites filled with Martian regolith. The on-line tool for the assessment of radiation in space (OLTARIS) software developed by NASA was used to assess the radiation shielding effectiveness of polyethylene (PE)/regolith (RG) composites in the Martian radiation environment. A basalt powder with chemical composition similar to that of Mars soil was used as Martian regolith simulant in the 3D printing process. Differential scanning calorimetry (DSC) was used to determine the melting properties and crystallization degree of PE/RG composites at different RG concentrations, in order to analyze the effect of the simulant on the process parameters of filament extrusion and 3D printing. Low-impact Izod tests were also performed, with all PE/RG composites showing improved impact strength with respect to neat PE. Based on the DSC and Izod tests results, filaments of PE/RG composites were fabricated and used to 3D-print samples for tensile tests and 3-point bending tests. Results demonstrate the radiation shielding effectiveness of PE/RG composites and the capability of 3D-printers based on FFF to successfully manufacture components made of PE/RG composites starting from extruded filaments