Assessment of environmental and health impacts during 3D printing of candidate polymeric materials for space additive manufacturing.

Polyether ether ketone (PEEK) and thermoplastic polyimide (PI) are candidate materials for space additive manufacturing. However, 3D printing with them in space station cabin will release particles and non-methane hydrocarbons (NMHCs), posing potential environmental and health impacts. This work characterized particles and NMHCs emissions in a simulated Teflon box. Both nano-sized and micro-sized particles, generated from the condensation and aggregation of gaseous degradation compounds with low volatility from filaments were observed. The major particle-bound compounds were hydroquinone and 4-phenoxydibenzofuran for PEEK, and 3-hydroxyphenol and 4-isocyanatophenol for PI. The main NMHCs released from 3D printer were n-butane, xylene, acetone, and acrolein, etc. Benzene, toluene and acetaldehyde were main NMHCs released from PEEK and PI. Emission was enhanced with higher chamber and bed temperatures and the addition of trisilanolphenyl polyhedral oligomeric silsequioxane. Printing with PEEK poses high respiratory and carcinogenic risks due to high alveolar particle deposition rate and benzene emissions; and printing with PI carries carcinogenic risks due to high acetaldehyde emissions. Feasible solutions, such as addition of circulating filtration part to 3D printer and purification of polymer, were provided to reduce emissions. This work provides new insights into the environmental and health impacts of space 3D printing of polymers.