Tailoring the Mechanical Properties and Foaming Behaviors of <scp>PLA</scp>/<scp>P4HB</scp> Blends by Using <scp>P4HB</scp>‐g‐<scp>GMA</scp> as Compatibilizer

ABSTRACT Synthetic poly(4‐hydroxybutyrate) (P4HB), a flexible and biodegradable polymer, shows great promise in improving the toughness of poly(lactic acid) (PLA), but the inherent immiscibility of PLA and P4HB compromises the toughening efficiency. To address this issue, P4HB grafted glycidyl methacrylate (P4HB‐g‐GMA) is synthesized for the purpose of enhancing the compatibility within the PLA/P4HB blend. The epoxy groups on P4HB‐g‐GMA can form strong chemical bonds with PLA chains and remain compatible with P4HB. Rheological data confirm that adding P4HB‐g‐GMA enhances polymer chain entanglement. Therefore, the phase interface of the blend becomes more diffuse, leading to improved mechanical performance. Specifically, a 3D‐printed PLA/P4HB/P4HB‐g‐GMA blend containing 8% P4HB‐g‐GMA (PLA/P4HB/G8) achieves an elongation at break of 161.5%, approximately 22.7 times higher than that of a PLA/P4HB blend without the modifier. Moreover, the PLA/P4HB/G8 blends show a higher volume expansion ratio (VER) and better cell morphology due to the increased melt strength from P4HB‐g‐GMA. This study demonstrates a simple and efficient method to improve the compatibility between PLA and P4HB, resulting in superior mechanical performance of PLA/P4HB blends and broadening their potential applications in foaming.