Lignin modified PBAT composites with enhanced strength based on interfacial dynamic bonds

Abstract Poly(butylene adipate‐co‐terephthalate) (PBAT) is a type of synthetic biodegradable thermoplastic copolyester with comparable mechanical properties to polyethylene, but the application of PBAT is limited by factors such as high cost, short shelf life, poor weather and water resistance. In order to develop PBAT composites with high performance and low cost, lignin‐modified PBAT biocomposites with enhanced tensile strength were prepared via in‐situ construction of interfacial dynamic bonds. Zinc stearate and epoxy soybean oil were introduced as the interfacial modifiers to construct dynamic bonds between lignin and PBAT, so as to improve the interfacial compatibility. The results demonstrated that the lignin/PBAT biocomposite with interface modifiers reached the maximum tensile strength of 36.7 MPa and an elongation at break of 725.3% at the lignin content of 5 wt%, with the tensile strength achieved 5% improvement on the basis of pure PBAT (34.9 MPa and 717.6%). When the lignin content was increased to 10 wt%, the lignin/PBAT biocomposite with interfacial modifiers still maintained the tensile strength of 35.4 MPa and the elongation at break of 627.8%, which was 82% and 31% higher than that of the directly compounded sample without interfacial modifiers, respectively. Even when the content of lignin loading increased to 20 and 30 wt%, the mechanical properties of the composites were still significantly improved by adding modifiers. The hydrophobicity of the composite was also improved after in‐situ interfacial modification. The strategy demonstrated in this work provides an effective reference for the development of lignin/PBAT composites with high performance but low cost.