Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Green PET was depolymerized via reactive extrusion glycolysis, recovering BHET as the main monomer. The process was validated by viscometry and confirmed through the isolation and characterization of BHET using IR, Raman, 1H-NMR, and XRD analyses. This approach highlights an efficient method for chemical recycling of colored PET waste into valuable monomeric precursors.

ABSTRACT
Chemical recycling of PET has been widely studied in batch processes; however, scale-up is energy-intensive. In this study, chemical recycling was employed to explore the recovery of BHET monomer from green PET via glycolysis using reactive extrusion. Experiments were conducted by varying both ethylene glycol and catalyst concentrations in a twin-screw extruder. The conditions achieved the decrease of instrinsic viscosity (< 0.26 dL g−1) and low monomer recovery (< 3.5%), separated from the green dye. BHET was identified by FT-IR, Raman, 1H-NMR, XRD, and DSC analyses; some contaminants remained in the monomeric fraction. Higher monomer yields were achieved either by carrying out a double-cycle extrusion (8.7%), or by using an extruder with a longer L/D ratio (9.3%). The results demonstrate that reactive extrusion is a viable strategy to reintegrate colored PET into the circular economy. However, further optimization is required to retain glycol within the barrel and increase monomer yield and purity.