Branched <scp>PBST</scp> /Lignin Composites With Enhanced Mechanical and Anti‐ <scp>UV</scp> Properties via In Situ Reaction and Metal Coordination Bond Compatibilization

ABSTRACT Branched poly(butylene succinate‐ co ‐terephthalate) (PBST)‐based composites, a kind of bioplastic incorporated with lignin and other auxiliary agents with excellent mechanical properties, were obtained through melting processing in this work. Wherein, the epoxy group in multifunctional styrene‐acrylic‐epoxy‐based random oligomer chain extender Joncryl ADR‐4468 (ADR) could react in situ with hydroxyl in lignin and branched PBST. Additionally, Zn 2+ from zinc stearate (ZnSt) could form metal coordination bonds with the oxygen‐containing functional groups of lignin and branched PBST. The in situ reaction and metal coordination bonds could improve the compatibility of the two. The tensile strength and the elongation at break could reach 18.6 MPa and 1224.7%, respectively, because of the increased compatibility. Moreover, the composites also exhibited hydrophobicity, excellent UV resistance, and visible light barrier properties. It is expected to have broad application prospects in the fields of agricultural mulch film and packaging.