Hydrothermal aging behavior of poly(butylene adipate-co-terephthalate) mulch: influence of the hydrolysis resistance based on the different filling materials

The microplastic pollution caused by traditional agricultural mulch had been revealed. The application of biodegradable mulch is one of the potential ways to solve this problem. Therefore, it is significant to investigate the hydrothermal aging behavior of poly(butylene adipate-co-terephthalate) (PBAT) mulch. In this study, thermoplastic starch (TPS), TPS/talc, and talc-filled PBAT mulch were prepared. A 28-day hydrothermal aging test was conducted, and the mechanical properties, light transmission, water vapor barrier properties, hydrophobic performance, viscosity-average molecular weight, and characterization of the PBAT mulch were detected. The results showed that the original TPS-filled PBAT mulch had excellent mechanical properties, and its tensile strength and elongation at break reached 29.67 MPa and 1166.52%, respectively. The mechanical properties of the PBAT mulch were greatly reduced after hydrothermal aging. Hydrothermal aging would reduce the light transmittance of PBAT mulch to visible light, while the hydrolysis of starch would cause the opposite result. The hydroxyl group in TPS would reduce the water vapor barrier performance of the PBAT mulch. After hydrothermal aging, the viscosity-average molecular weight of the PBAT mulch decreases and the surface of the PBAT mulch was destroyed, which meant that the PBAT mulch was hydrolyzed. FTIR showed that hydrothermal aging could cause the fracture of ester groups. The TG spectral curve showed that the proportion of TPS in PBAT mulch decreased after hydrothermal aging, which meant that TPS was more easily hydrolyzed than PBAT. The results would promote the wide application of PBAT mulch.

Graphical Abstract