Starch/PVA-based active packaging films with montmorillonite and lemongrass oil for improved mechanical and barrier performance

This work uses the solvent-casting approach to fabricate and evaluate eco-friendly films based on a starch/PVA (SP) matrix, loaded with montmorillonite clay (MMT) and lemongrass essential oil (LEO). The effects of each additive on the structural and morphological characteristics of bio-composite films were examined using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR analysis confirmed the incorporation of MMT and LEO in the SP matrix by the shifting of the characteristic peak to a lower wavenumber. The characteristic peak at 5.8° shifted to a lower angle in XRD, confirming the intercalation of MMT. The findings demonstrated that the tensile strength of nanocomposite films reinforced with 0.3% MMT improved by 59.06%; however, it decreased by 38.86% when MMT was increased to 0.7%, and the films became opaque and brittle. The incorporation of MMT into the starch/PVA polymeric blend increased the thermal stability of the developed films. SEM analysis confirmed that the particles were uniformly distributed throughout the matrix at a low nanoclay concentration. Furthermore, the integration of LEO into the SP/MMT-0.3 matrix reduced tensile strength and increased EB from 230% to 260%. The integration of MMT and LEO into the polymer matrix enhanced the film's water resistance by lowering moisture content (14.60%), solubility (11.25%), absorption (18.53%), and water vapour permeability (20.95%). Additionally, the fabricated films also exhibited antibacterial efficacy against E. coli (ZOI-11.2 mm) and S. aureus (ZOI-13.7 mm), while maintaining biodegradability. Moreover, the overall migration analysis for MMT clay lies within the permissible range. In conclusion, the synergistic incorporation of MMT and LEO significantly enhanced the physicochemical, barrier, structural, and functional characteristics of the SP matrix while preserving its biodegradable nature. These findings demonstrate the potential of the developed bio-composite film as a sustainable, active packaging material that may replace conventional non-biodegradable petroleum-based packaging.