Integrated Selective Depolymerization and Downstream Processing for Mixed Polyester Waste, Part 1

ABSTRACT The chemical recycling of polylactic acid (PLA) and polyethylene terephthalate (PET) mixtures by alkaline hydrolysis is investigated. Like most solvolysis processes, hydrolysis lacks selectivity, yielding dilute monomer mixtures that require elaborate downstream purification. To avoid downstream complexity, selective depolymerization is pursued by leveraging differences in polymer reactivity. Variation of temperature and base concentration relative to the base case (polymer‐to‐NaOH ratio 0.8 mol mol −1 , 90°C) increase selectivity by 17% and 14%, respectively, at the expense of reaction kinetics. The addition of a co‐solvent increases selectivity by 19% while reducing reaction time for PLA by 98%. These findings suggest that sequential depolymerization of PLA and PET can be attained by choosing suitable operating conditions.