Compatibilization of Thermoplastic Starch and Poly (Butylene Succinate‐Co‐Adipate) Blends Using a Dual‐Coupling Strategy

This study analyzed the effect of employing coupling agents in the development of acetylated thermoplastic starch (TPSA)—poly (butylene succinate‐co‐adipate) (PBSA) blends, addressing a research gap in TPSA‐predominant systems using a dual reactive strategy to improve compatibility with PBSA. Acetylated starch was plasticized with glycerol and blended with PBSA using tartaric acid (TA) and dicumyl peroxide (DCP) as coupling agents. The effect of these additives was evaluated by structural, mechanical, rheological, thermal, and morphological characterization of blends containing TA (0, 1, 2, and 5wt.%) and DCP (0, 0.5 and 1wt.%). TA promoted the esterification of the TPSA phase, leading to chemical modifications that altered the thermal and rheological behavior of the blends but produced only limited improvements in compatibility when used alone. In contrast, the addition of DCP promoted radical‐induced reactions that, according to the combined experimental evidence, were predominantly associated with chain scission, resulting in improved interfacial interactions, a more homogenous morphology and enhanced mechanical performance. The best performing formulations exhibited a tensile strength of up to 9.64 MPa and an elongation at break approximately five times higher than that of the control blend. Overall, the findings reveal a synergistic effect between TA and DCP in TPSA—PBSA blends, providing an effective compatibilization strategy for TPSA‐predominant blends and contributing to improving the performance of biodegradable polymer systems.