Enhancement of Biopolymer Film Properties Using Spermidine, Zinc Oxide, and Graphene Oxide Nanoparticles: A Study of Physical, Thermal, and Mechanical Characteristics

One of the main limitations of biopolymers compared to petroleum-based polymers is their weak mechanical and physical properties. Recent improvements focused on surmounting these constraints by integrating nanoparticles into biopolymer films to improve their efficacy. This study aimed to improve the properties of gelatin–chitosan-based biopolymer layers using zinc oxide (ZnO) and graphene oxide (GO) nanoparticles combined with spermidine to enhance their mechanical, physical, and thermal properties. The results show that adding ZnO and GO nanoparticles increased the tensile strength of the layers from 9.203 MPa to 17.787 MPa in films containing graphene oxide and zinc oxide, although the elongation at break decreased. The incorporation of nanoparticles reduced the water vapor permeability from 0.164 to 0.149 (g.m⁻².24 h⁻¹). Moreover, the transparency of the layers ranged from 72.67% to 86.17%, decreasing with higher nanoparticle concentrations. The use of nanoparticles enhanced the light-blocking characteristics of the films, making them appropriate for the preservation of light-sensitive food items. The thermal properties improved with an increase in the melting temperature (Tm) up to 115.5 °C and enhanced the thermal stability in the nanoparticle-containing samples. FTIR analysis confirmed the successful integration of all components within the films. In general, the combination of gelatin and chitosan, along with ZnO, GO, and spermidine, significantly enhanced the properties of the layers, making them stronger and more suitable for biodegradable packaging applications.