Enhanced Multifunctional Properties of Polypropylene/Bi2O3 Nanocomposites for Energy Storage and Packaging Applications

Abstract

This study reports the development of multifunctional polypropylene (PP) nanocomposites reinforced with Bi2O3 nanoparticles synthesized via the solvothermal method. Structural characterization of Bi2O3 was carried out by XRD, TEM, and FTIR. Nanocomposites containing 0.5-5 wt% Bi2O3 were fabricated using extrusion and hot-pressing, and their optical, morphological, electrical, and mechanical properties were systematically investigated. UV-Vis analyses revealed a reduction in band gap and an increase in refractive index, extinction coefficient, and optical conductivity with increasing Bi2O3 content. Electrical measurements indicated improved energy storage capability, particularly at 5 wt% Bi2O3 loading, while maintaining low dielectric loss. Mechanical tensile tests showed that 5 wt% Bi2O3 increased Young's modulus by 49.5% compared to pure PP, improving stiffness and rigidity, whereas 0.5 wt% Bi2O3 enhanced stress at break and strain at break, indicating improved toughness and ductility. Wettability measurements revealed a hydrophobic transition at 0.5 wt% and a return to hydrophilic behavior at higher loadings, consistent with surface roughness trends. Overall, the results demonstrate that Bi2O3 nanoparticle-reinforced PP nanocomposites exhibit synergistic improvements in optical, dielectric, and mechanical performance, making them promising candidates for lightweight structural components, durable flexible packaging, and advanced dielectric energy storage devices.