Enhanced Compatibility of Waste PET/PBAT Composites via Polyurethane Compatibilizers: Structure and Properties

ABSTRACT Recycling waste polyethylene terephthalate (PET) into value‐added materials remains an important strategy for reducing plastic pollution and improving resource sustainability. In this study, waste PET and biodegradable plastic poly (butylene‐adipate‐co‐terephthalate) (PBAT) were reactively melt blended using three polyurethane‐based polymers as compatibilizers to improve interfacial compatibility. The effects of compatibilizer type and PET content on the structure and properties of the composites were systematically investigated. It was found that PBAPU‐H exhibited the most significant improvement in ductility and toughness of the PET/PBAT blends due to its flexible long‐chain structure, whereas COPU provided higher tensile strength and elastic modulus. The infrared spectroscopy, thermal stability, tensile test, and SEM observations combined with ImageJ quantitative analysis confirmed that polyurethane compatibilization significantly reduced the interfacial void area fraction and enhanced the interfacial adhesion between PET and PBAT. In particular, the composite containing 60 wt% PET exhibited the best overall performance, with elongation at break of 258.61% and an elastic modulus of 2927.20 MPa. This study offers a cost‐effective solution for repurposing waste PET, promoting sustainable plastic use and contributing to the global effort to reduce plastic pollution.