Conventional filament extrusion processes are unsuitable for recycling materials on the International Space Station due to requirements for continuous monitoring and tuning, as well as poor filament dimensional control. The Positrusion process recycles scrap or waste thermoplastics into filament for 3D fused filament fabrication (FFF) printers.

The first half of Positrusion is called the processing chamber, which reprocesses arbitrary geometries of plastic materials, such as pellets or scrap parts, into a stream of molten plastic. The second half of Positrusion is called the continuous molding module, which forms and cools/solidifies the plastic into a very-high-quality constant cross-section product. An automatic spooling mechanism winds the produced filament.

One novelty of this process is the use of continuous molding to form a dimensionally controlled filament. It uses the application of vacuum during melting of plastic parts to extract gases and other contaminants, as well as a gear pump to finely control the material feed rate.

Applications include recycling of waste plastics into 3D printer filament in the home and office.

This work was done by Jesse Cushing, Jeffrey Slostad, Robert Hoyt, and Kristen Turner of Tethers Unlimited Inc. for Marshall Space Flight Center. For more information, contact Ronald C. Darty, Licensing Executive in the MSFC Technology Transfer Office, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS-33252-1.


NASA Tech Briefs Magazine

This article first appeared in the December, 2015 issue of NASA Tech Briefs Magazine.

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