Green composites for sustainable food packaging: Exploring the influence of lignin-TiO2 nanoparticles on poly(butylene adipate-co-terephthalate)

Titanium dioxide (TiO2) is a common pigment used in food packaging to provide a transparent appearance to plastic packaging materials. In the present study, poly(butylene adipate-co-terephthalate) (PBAT) incorporated with lignin-TiO2 nanoparticles (L-TiO2) eco-friendly composite films was prepared by employing an inexpensive melting and hot-pressing technique. The P-L-TiO2 composite films have been studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), Thermogravimetric analysis (TGA), and Differential scanning calorimetry (DSC) analysis. The FTIR results and homogeneous, dense SEM images confirm the interaction of L-TiO2 with the PBAT matrix. It has also been found that the addition of LTiO2 nanoparticles can increase the crystallinity, tensile strength, and thermal stability of PBAT. The addition of L-TiO2 increased the tensile strength and decreased the elongation at break of films. The maximum tensile strength of the film, achieved with 5 wt% L-TiO2, was 47.0 MPa, compared with 24.3 MPa for pure PBAT film. The composite film with 5 wt% L-TiO2 has outstanding oxygen and water vapor barrier properties. As the content of lignin-TiO2 increases, the antimicrobial activity of the composite films also increases; the percentage of growth of all the tested bacteria Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli) is significantly reduced. Strawberries were packed to evaluate the suitability of produced composite films as packaging materials, as they effectively preserved pigments from accumulation and extended the shelf-life as compared to commercial polyethylene packaging film.