Development of <i>poly(lactic acid)</i> nanocomposite films with <i>kaolin/bentonite</i> blended <i>clay</i> for packaging applications

In this study, <i>Kaolinite clay</i> from the North-East Region (NER) of India was blended with <i>bentonite clay</i> and incorporated into <i>poly(lactic acid) (PLA)</i> at different concentrations of: 1%, 3%, 5%, and 7 weight% (wt%) through the <i>solvent casting method</i>. The resulting films were characterized by using the <i>Fourier transform infrared (FTIR)</i> spectroscopy to investigate the interactions among the various functional groups. The <i>X-ray diffraction (XRD)</i> analysis was performed to determine the composites’ structure and <i>crystallinity</i>, while the <i>thermogravimetric analysis (TGA)</i> was employed to assess the thermal stability of the films. Furthermore, mechanical properties, such as the <i>tensile strength, Young’s modulus, and elongation-at-break</i> (%) were evaluated. The maximum <i>tensile strength</i> of 36.9 MPa was attained for the <i>PLA</i> film blended with 7 wt% of <i>clay</i>. However, the <i>elongation-at-break</i> (%) for this specimen was lower when compared to the neat PLA film. <i>Field emission scanning electron microscopy (FE-SEM)</i> analysis provided insights into the morphology of the poly(lactic acid)–NER <i>kaolinite/bentonite</i> blend <i>clay</i> nanocomposite films, thereby revealing significant aggregation and <i>agglomeration</i> within the specimen containing the 5 wt% of filler. Moreover, the packaging application of the films developed was evaluated to enhance the shelf life of fresh black grapes. The results revealed that the unpackaged grapes experienced spoilage, while those wrapped in the films (PLA-7%) developed and showed no signs of deterioration after the 14 days of storage at room temperature. These findings suggest that the newly developed nanocomposite films could serve as an effective option for fruits packaging applications.