Low-temperature chemical upcycling of poly(ethylene terephthalate) waste to recyclable polyurethane thermosets using biomass-derived materials
Jihong Lyu, Seulchan Lee, Hyocheol Jung, Young Il Park, Jingi Ahn, Young‐Jae Jin, Ji‐Eun Jeong, Jin Chul Kim
Abstract
Addressing the global challenge of plastic waste, particularly poly(ethylene terephthalate) (PET), requires innovative chemical upcycling strategies. In this study, we report a sustainable approach for transforming PET waste into chemically recyclable polyurethane (PU) thermosets. Using a low-temperature glycolysis process with potassium carbonate , 1,4-butanediol and chlorobenzene, bis(4-hydroxybutyl) terephthalate (BHBT) was obtained with a conversion rate exceeding 99 % and an isolated yield of 55.4 %. The BHBT was subsequently used to synthesize PU thermosets with bio-based pentamethylene diisocyanate trimer and 2-methyltetrahydrofuran as a solvent. The resulting thermosets demonstrated excellent mechanical properties, including a tensile strength of 21.8 MPa, elongation at break of 151 %, and a Young’s modulus of 279 MPa. The PU thermosets were chemically recyclable, enabling a closed-loop process where BHBT was recovered with 84.5 % yield via glycolysis. Furthermore, the BHBT-based PU thermosets were successfully applied to carbon fiber-reinforced polymer composites, maintaining their mechanical integrity after recycling. This work highlights a promising route for the upcycling of PET waste, contributing to the development of sustainable polymer materials and supporting the principles of a circular economy.