Enhanced properties of PBAT/TPS biopolymer blend with CuO nanoparticles for promising active packaging

Blending poly(butylene adipate-co-terephthalate) (PBAT) with thermoplastic starch (TPS) has been extensively investigated for cost reduction and better biodegradability. However, film blend showed poor thermal, mechanical and barrier properties. The feasibility of incorporating copper oxide nanoparticles (CuONPs) at concentrations ranging from 0.05% to 2% to reinforce PBAT/TPS (70:30) films was studied. Melt flow index of the blend increased from 3.52 to 7.24 g/10 min as the CuONPs concentration increased, resulting in a decrease in torque during the blown-film extrusion. Scanning electron microscopy with energy-dispersive X-ray analysis and X-ray diffraction indicated that CuONPs were located in the TPS phase without modification of the crystalline structure. CuONP addition improved the thermal stability of PBAT/TPS by shifting the degradation temperature at T10% to a higher zone. During heat sealing, high conductivity of Cu promoted interfacial interactions across the film surfaces, resulting in stronger sealing. At 2% CuONPs, tensile strength increased by 29.1%, while Young’s modulus increased by 9.3% compared to PBAT/TPS. The hydrophilicity of TPS significantly reduced oxygen permeability of pristine PBAT by 28.7%, while low CuONP concentrations promoted the gas diffusion rate. Higher CuONP concentrations created more tortuous paths, increasing the oxygen barrier of the bionanocomposites to PBAT/TPS levels. Inclusion of CuONPs also improved the water vapor barrier property of PBAT/TPS films. The bionanocomposite film showed effective antibacterial activity against Escherichia coli (99.7% reduction). These findings suggest that the PBAT/TPS-CuO bionanocomposite film can be feasibly produced and used in food packaging to preserve the food quality and extend the shelf-life of product.