Nanoparticles From Infusion Beverage Wastes and Their Effect on PLA/PHB Plasticized Composite Behavior

In this work, yerba mate (nYM) and black tea (nBT) nanoparticles were extracted from Ilex paraguariensis and Camellia sinensis, respectively. Unlike traditional biocomposites and additives, this approach valorizes the waste of infusion beverages without using chemical compounds. Nanoparticles underwent preliminary TGA analysis, showing stable and high degradation temperature, making them suitable for processing with the selected polymer matrix. Subsequently, they were incorporated into the selected PLA (75%)–PHB (25%) blend plasticized with maleinized corn oil (MCO) at a concentration of 1–3 wt.%. Tensile characterization of the PLA-PHB blend plasticized with MCO showed an improvement in compatibility between polymers, with increased ductility. The plasticizing effect of MCO was confirmed by calorimetric analysis, showing a remarkable decrease in Tg value. The combination of MCO and nanoparticles continues to exhibit enhanced thermal stability, showing functional nanofiller behavior. Moreover, the presence of nanoparticles enhanced the barrier property of the plasticized films toward oxygen barrier properties, reducing the OTR-e values. Finally, during the second half of the composting test, it was observed that nanoparticle addition delayed the degradation process; otherwise, it continued showing interesting biodegradable properties. These findings open multiple possibilities in the combined use of infusion beverage waste nanoparticles and modified vegetable oils to develop sustainable packaging applications.