Teaching Space-Borne Recycling to Middle School Students via 3D Printing - Managing Classroom Air Quality

摘要

In 2014, the digital file for a needed 4.48-inch ratcheting wrench was sent from designers on Earth to the 3D printer on the International Space Station (ISS). The wrench was fabricated on ISS in less than four hours without need to wait for an Earth resupply mission; it was the first useful tool 3D printed in space. Emerging space-borne manufacturing facilitated by 3D printing strongly parallels terrestrial residential recycling programs. These similarities are being leveraged to create a recycling-focused learning module for middle school students at Ignite School House, an educational non-profit organization. By studying why recycling is valuable and how it is accomplished in the closed and highly-controlled environment of a manned space vehicle, middle school learners internalize why terrestrial residential recycling programs are important for energy and resource preservation on Earth. In the middle school module, plastic waste will be recycled into 3D printer filament, which will then be used to 3D print custom objects valuable for education. To advance this program, Ignite School House and social enterprise Engineer Inc. created Customer Needs specifications for a custom-built multi-material filament extruder to perform the plastic recycling process. Indoor classroom air quality near operating filament extruders and 3D printers emerged as a critical unresolved human health concern. However, safe indoor air quality parameters for terrestrial filament extruders and 3D printers have not yet been established. To quantify air pollution levels for the Ignite School House classroom, concentrations of particulate matter, formaldehyde, and total volatile organic compounds were experimentally measured for an unenclosed 3D printer. ABS filament was found to the most polluting, followed by PETG then PLA. Further testing using an open source IKEA Lack table enclosure and a fan-vented enclosure demonstrated that these enclosure barriers are generally effective in reducing indoor air pollution during 3D printing. These results recommend that all classroom-based 3D printers and filament extruders be enclosed, at least until safe air quality levels for human health are established for these technologies.