3D Printed Materials Characterization for Rapid Prototyping and Plant Growth

Low temperature 3D printing (<300 ̊C) technologies have become more affordable and accessible to everyday users and researchers. The result is an increased application of 3D printed plastics into prototyping and experimental hardware. The NASA Space Biology and Space Crop Production team at KSC have taken advantage of this by incorporating low temperature 3D printed thermoplastic filaments into the development of a controlled environment (CE) and experiment-unique equipment plant growth hardware as a means of increasing development and saving time and resources. As a recently adopted capability, references for characteristics of 3D printed materials (when applied to plant growth systems) are limited to experiments using polylactic acid (PLA), or acrylonitrile butadiene styrene (ABS) to create experimental hardware such as for NASA’s Random Positioning Machine (Zhang, 2021), or the IRTD 2021 Microgreens Root-Shoot Separator Boxes project made from 3D printed PLA and used to harvest microgreens on parabolic flights (Poulet, 2022). As the technology becomes more widely used and additional types of thermoplastic filaments become available, it is vital to understand how these materials behave under relevant scenarios like sanitization, exposure to nutrient solutions, tendency to form biofilms, and the ability to withstand heat and force. This study compiled a list of off -the-shelf thermoplastic and composite filaments (printed at <300 ̊C nozzle temperature) and ran a series of tests to document properties and characteristics under conditions relevant to CE plant growth. The research team identified and printed 18 filaments in the Plant Processing Area (PPA) in the SSPF. After initial assessment, nine filaments were down selected as the most used industry wide or having potential beneficial properties for space plant biology/crop production use. Characterization of the nine thermoplastic filaments was conducted using printed test specimens in three laboratories (KSC Analysis/Mechanical and Environmental Testing Laboratory for materials testing, KSC Molecular and Microbiological Laboratory for microbial testing, and KSC PPA for plant growth and spectral testing). Materials were scrutinized under various test conditions to assess meeting TRL 6 for plant growth applications.