Production and Characterization of Eco-composite Polylactic Acid Films Doped with Carob Pod Powder/Silver Nanoparticles and Their Potential Utilization in Packaging Applications

Abstract

This study aims to determine the influence of carob pod powder (CP) on antimicrobial performance, thermal behavior, mechanical strength of poly-lactic acid (PLA) matrix to observe the utilization potential as an environmentally-friendly eco-composite packaging material. Subsequent to pretreatment of CP and PLA, silver nanoparticles (AgNPs) were introduced into PLA matrix. Single-stage extruder was used to enable continuous sheet extrusion and material compounding to procure three different samples of 100 wt% PLA, 80 wt% PLA-20 wt% CP, and 75 wt% PLA-20 wt% CP-5 wt% AgNPs in pellet form. Extruded pellets underwent injection molding for tensile strength tests. The samples were characterized via Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FT-IR) analyses. Dynamic Mechanical Analysis (DMA) was carried out on the specimens to achieve glass transition behavior of the samples and compare them to those of Differential Scanning Calorimetry (DSC). Thermo-gravimetric (TG) analysis was conducted to observe thermal stability. Thickness and surface roughness were analyzed using profilometer. Antibacterial performance of eco-composites against Staphylococcus (S. aureus) and Escherichia coli (E. coli) was investigated. Combined effects of pretreated CP and AgNPs incorporation in PLA matrix resulted in 20% increase in tensile strength, 2.2% increase in glass transition temperature. The death rates of E. coli and S. aureus were found to be 87.3%, and 81.3%, respectively. Promising outcomes in the fabrication of packing materials with high sterilization and resilience against heat and mechanical stress were obtained through the combined influence of sample features with accuracy and appropriate parameters in extrusion process.