Effect of greenly synthetized silver nanoparticles on the properties of active starch films obtained by extrusion and compression molding

Abstract

Replacing packaging plastics with biodegradable active materials is an emerging concern. In this context, thermoplastic starch (TPS) films and nanocomposites containing different concentrations of silver nanoparticles synthetized with starch and yerba mate (TPS-AgNP₁: 0.006 wt.% and TPS-AgNP₂: 0.015 wt.%) were developed by extrusion and compression molding. Spherical AgNP of 20-130 nm were obtained after the green synthesis and excellent adhesion between AgNP and the matrix was observed. Consequently, both composites exhibited higher stiffness and tensile strength values than TPS, indicating a reinforcing effect of AgNP. TPS-AgNP₁ showed the highest strain at break and toughness values, and TPS-AgNP₂ presented the lowest moisture content and ability to delay E. coli growth. Additionally, all materials disintegrated after 4 weeks of burial and resulted thermally stable up to 240 °C. This investigation provides a convenient and inexpensive way to develop starch-based nanocomposites with improved properties which appear to be promising as active packaging materials.

Keywords: Active starch-based nanocomposites; Antibacterial activity; Extrusion and compression molding; Green synthesis; Physicochemical properties; Silver nanoparticles.