In this work, an organophosphorus flame retardant (BHD) was synthesized using 4‐formylphenylboronic acid and 1,6‐hexanediamine; a charring‐coupling agent containing epoxy (DE) was synthesized using daidzein and epichlorohydrin. The BHD and DE were reacted and coated on the surface of aluminum diethylphosphinate (ADP) and the product is identified as BD‐ADP. PA6 with 12 wt% BD‐ADP achieves a UL‐94 V‐0 rating and a limiting oxygen index (LOI) value of 30.0 vol%. Substitute 1.0 wt% DE for BD‐ADP, PA6‐1.0E not only achieves a UL‐94 V‐0 rating, but also goes out before dripping. The time to ignition of PA6‐1.0E is 19 s longer than that of PA6. The flame‐retardant mode is the combination of the gas‐phase effect of ADP and the condensed‐phase effect of DE. In addition, the tensile strength and impact strength of PA6‐1.0E are 103.9 MPa and 6.6 kJ/m2 which are 35.6% and 43.5% more than that of PA6‐12A. Both BD coating and DE contribute to a strong interfacial adhesion between ADP and PA6 which improves the mechanical properties. The DE plays a key role in the flame retardancy and mechanical properties of PA6 blends.

The block copolymers PEF/PBAT were synthesized by copolymerizing ethylene 2,5-furandicarboxylate (EF) with totally biodegradable poly (butylene adipate-co-terephthalate) (PBAT). The copolymers' molecular chain structure, thermal properties, thermal stability, and mechanical properties were investigated, and the toughening mechanism was preliminarily studied via the micromorphology. The results revealed that the prepared block copolymers were amorphous, the thermal stability of PEF was improved, while the glass transition temperature decreased with the increase of PBAT content. PBAT was enhancing the tensile strength and elongation at break of PEF simultaneously. When the PBAT content was 25% (PEF/PBAT-25), the brittle-ductile transition occurred, with the tensile strength, Young's modulus and elongation at break of 72 MPa, 3210 MPa and 287%, respectively. The copolymers have broad application in the field of packaging materials. K E Y W O R D Sbio-based polyester, block copolymers, brittle-ductile transition, poly (butylene adipate-coterephthalate), thermal properties