Enhanced Sustained‐Release Antibacterial Activity in PBAT Composite Films via Ultrasound‐Freezing Pretreatment of Bamboo Fiber

ABSTRACT Enhancing the functionality of biodegradable packaging is key to driving its replacement of conventional plastics. In this work, we employed ultrasound and ultra‐low‐temperature freezing technology to pretreat bamboo fiber (BF), resulting in a carrier with significantly enhanced specific surface area and pore volume to effectively improve the loading capacity of cinnamon essential oil (CEO). Poly(butylene adipate‐co‐terephthalate) (PBAT) was used as a matrix; the BFs/PBAT/CEO film was produced by utilizing melt extrusion and blow molding processes. The addition of BF not only served as a carrier for CEO but also significantly accelerated the film's degradation. Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Thermogravimetric Analysis (TGA) were employed to investigate the morphology, structure, and sustained release of the CEO. The pretreated BF has a significant increase in surface area (20.37 m 2 /g) and pore volume (0.1619 cm 3 /g). Moreover, the BFs/PBAT/CEO film has a higher loading capacity (2.6%) for CEO compared to untreated BF via the vacuum‐assisted physical loading. The produced films have irregular shapes and embossment on the surface, representing an excellent Tensile Strength (TS) (31.003 MPa) and Elongation at Break (EAB) (376.599%). Meanwhile, the flexible films show outstanding antimicrobial activity against both Staphylococcus aureus and Escherichia coli in contact as well as non‐contact conditions. The aforementioned properties of BFs/PBAT/CEO films enable their application in tofu packaging, achieving significant preservation efficacy with a notable extension of shelf life.