Bio-based nanocomposite films were developed using poly(vinyl alcohol) (PVA) reinforced with tragacanth gum (TG) and carboxymethyl tragacanth (CMT), incorporating biogenic ZnO or CuO nanoparticles and plant-derived extracts (cinnamon or clove). A comparative evaluation of structural, surface, mechanical, and oxygen barrier properties was conducted to assess their potential for active food packaging. FESEM analysis revealed that CMT-based films possessed a more homogeneous and compact microstructure with fewer microcracks compared to TG-based films. The lower contact angle observed for CMT-containing films indicated stronger intermolecular interactions and a denser polymer network. CMT-based films demonstrate a more favorable balance between strength and elongation, resulting in improved toughness and mechanical stability, which are critical for flexible food packaging applications. Oxygen permeability measurements demonstrated that optimized CMT-based film achieved a lower oxygen transmission rate (26.80 cm³/m²·24 h·0.1 MPa) than TG-based film (27.53 cm³/m²·24 h·0.1 MPa), despite reduced thickness (70 μm versus 78 μm). Analysis of diffusion and solubility coefficients indicated that reduced oxygen solubility within the CMT matrix (2.66 × 10-10 cm3/cm2.cm.Pa) was the dominant factor governing overall permeability. The practical performance of the films was further assessed by coating raw pistachios. The optimized CMT-based film preserved the visual quality of pistachios for up to 12 days under ambient conditions without observable deterioration. These results highlight CMT-based nanocomposite films as promising sustainable materials for oxygen-sensitive food packaging applications.
Vafa et al. (Sun,) studied this question.