Design of Functional Modules in PBAT Molecular Structure and Their Performance Investigation

Abstract Fully biodegradable materials are of paramount importance in addressing the global “white pollution” crisis owing to their excellent degradation properties. Poly(butylene adipate-co-terephthalate) (PBAT), which exhibits good thermal stability, excellent impact toughness, and outstanding biodegradability, is widely recognized as one of the most promising alternatives to nonbiodegradable commodity plastics such as conventional polyethylene. Nevertheless, the mechanical properties, molecular weight, photostability, and processing properties of PBAT still require further optimization. Herein, during the synthesis of PBAT, branched structural units and photostabilizing units were incorporated into its molecular chains to enhance its mechanical properties and photostability. The results showed that when 1,2-hexanediol was used as the branching unit, the tensile strength of the synthesized branched PBAT increased from 27.3 to 49.1 MPa, the intrinsic viscosity increased to 1.77 dL·g–1, and the melt flow index decreased to 3.1 g·(10 min)−1; when the photostabilizer content was 0.3%, the weight-average molecular weight reached 14.4 × 104 g·mol–1. After ultraviolet aging, the tensile strength retention was as high as 24.5%, and the elongation at break retention was 10.5%, demonstrating excellent photostability. The successful incorporation of functional modules into PBAT molecular chains provides an effective approach for improving both mechanical properties and photostability. The enhanced resistance to UV aging enables better property retention during service, which may help extend the usable lifetime of PBAT-based products and support the broader application of biodegradable polymers in practical environments.