Interface-enhanced effect for constructing high-performance all-bio-based blends: poly(glycidyl methacrylate) compatibilization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/bio-based thermoplastic copolyester elastomer

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a representative bio-based biodegradable polyester; however, its high crystallinity and brittleness severely restrict its practical applications. To improve its mechanical performance, a thermoplastic copolyester (TPC) elastomer (ET) was used as a toughening agent, and a reactive interfacial compatibilizer—poly(glycidyl methacrylate) (PGMA)—was synthesized to enhance interfacial adhesion between PHBV and the TPC ET, improving their compatibility. Differential scanning calorimetry and Fourier transform infrared spectroscopy analyses indicated that the epoxy groups of PGMA formed hydrogen bonds with the PHBV and TPC ET phases, strengthening intermolecular interactions and restricting blend crystallization. Rheological and scanning electron microscopy results revealed that the incorporation of PGMA improved the interfacial bonding, refined the dispersed-phase size, and produced a uniform sea–island morphology. Consequently, the mechanical properties of the PHBV/TPC ET/PGMA blends considerably improved: the impact strength reached 17.58 kJ m−2, elongation at break reached 8.23%, and tensile strength reached 27.5 MPa—representing improvements of 270.1%, 69%, and 190.4%, respectively, compared with those of pristine PHBV. The proposed strategy effectively toughens PHBV and increases its application potential in sustainable polymer materials.