Chemical Recycling of Poly(butylene adipate- co -terephthalate): A Glycolysis–Repolymerization Approach

Abstract

Chemical recycling of bioplastics like poly(butylene adipate-co-terephthalate) (PBAT) promotes a circular economy by overcoming mechanical recycling limitations. This study investigated PBAT glycolysis and subsequent repolymerization of crude glycolyzed products, integrated with an early-stage life cycle assessment (LCA) using OpenLCA software with the ReCiPe 2016 Midpoint (H) impact assessment method to anticipate potential environmental impacts and sensitivity of the system. Glycolysis was conducted at 150–190 °C using Sn(Bu)2O (0.15 to 1.40 mol %) and NaHCO3 (5.0 mol %), presenting a Lewis acid coordination mechanism and a base-assisted glycolysis pathway, respectively, with ethylene glycol or 1,4-butanediol (4:1 molar ratio). Parameters including molar mass distribution (Mn, Mw, and Đ), species profile, and monomer yield were evaluated. Full conversion of the polymeric matrix was achieved within 2–5 h, leaving no detectable high-molecular-weight PBAT and yielding a mixture of oligomers and monomers, even at low catalyst concentrations (0.15 mol %), yielding oligomers with Mw of 0.6–1.4 kDa and up to 26.6 wt % monomer fraction. Notably, repolymerization without preliminary purification achieved Mw up to 10.6 kDa, comparable to 11.5 kDa reached using virgin raw materials. LCA results demonstrated improvements in 14 impact categories, with reductions between 6% and 35%. While fossil resource scarcity, ozone formation (human health and terrestrial ecosystem), and global warming potential increased due to the fossil-intensive energy baseline, the chemical proof of concept of directly utilizing crude glycolyzed products highlights the potential of this one-pot route to mitigate environmental burdens in polyester recycling, pending further property optimization.