Sustainable polymer reclamation: recycling poly(ethylene terephthalate) glycol (PETG) for 3D printing applications

Abstract Due to their versatile properties and wide-ranging applications across various industries, including manufacturing, polymers are indispensable for today’s society. However, polymer-based products significantly impact the environment since many are single-used plastics and require a long time to degrade naturally. A method to attenuate end-of-life polymers’ ill effects is recycling them to bring them again into the production cycle, from grave to cradle. This investigation involves recycling PETG sheets used in face shield production during the COVID-19 outbreak to fabricate 3D printing filaments for FFF. We assessed poly(ethylene terephthalate) glycol (PETG) processability to up to five recycling cycles and obtained filaments with properties adequate for 3D printing. Rheological, thermal, morphological, and mechanical characterization were analyzed to verify the effect of the number of processing cycles on the properties of the polymer. The recycling cycles originated a decrease in viscosity and elasticity, and the gain in molecular mobility resulted, relatively, in solids with a higher degree of crystallinity and prints with more elliptical depositions. The mechanical properties of printed parts fabricated of recycled material were comparable to those from commercial filament, especially after three extrusion cycles. Both extrusion and additive manufacturing processes successfully recycle material into filaments and printed parts, indicating that the proposed methodology is a promising alternative to bring value back to polymers from solid waste.