Tannic acid as a green and biodegradable crosslinker for tailoring toughness in poly(butylene adipate-co-terephthalate)/plasticized cellulose acetate blends

In contrast, in blends with higher pCA content, TA increased rigidity and strength, with Young’s modulus, flexural modulus, tensile strength, and flexural strength improving by approximately 48-54%, although ductility was reduced. These contrasting responses demonstrate that TA can shift the stiffness-toughness balance depending on blend composition. Thermal, rheological, morphological, and surface analyses indicated that TA modified hydrogen-bond-driven interactions and the resulting structure-property relationships.

Transmission electron microscopy further showed that TA was distributed within the polymer phases rather than selectively localized at the PBAT/pCA interface, confirming that it did not behave as a conventional interfacial compatibilizer. Instead, TA acted as a phase-dependent plasticizing/crosslinking additive, enabling tunable mechanical performance in biodegradable PBAT/pCA blends. This work provides a sustainable melt-processable strategy to design biodegradable packaging materials using a multifunctional green additive.