Mechanical Properties of <scp> Bi ₂ O ₃ </scp> / <scp>CuO</scp> Polypropylene Composite

ABSTRACT A new class of polypropylene (PP) composites reinforced with binary oxide fillers (Bi 2 O 3 ‐CuO) was synthesized via compression molding. To the best of our knowledge, this is the first report on Bi 2 O 3 ‐CuO/PP composites, exploring both bulk and nanoparticle forms of the oxide fillers. Various amounts (5, 10, 15, and 20 wt%) of bulk and nanoparticles (Bi 2 O 3 ‐CuO) obtained via a mechanical process were used as fillers in PP. The prepared PP composites were characterized using X‐ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDX). Structural characterization via XRD, UV–vis, FTIR, and SEM/EDX confirmed the successful dispersion and morphological integration of the oxide fillers within the PP matrix. The mechanical properties of the composites were investigated using Vickers microhardness and tensile stress–strain tests. They were significantly enhanced with increasing filler content, particularly with nano‐sized fillers. Vickers microhardness increased by up to 32.44% for nano‐filled composites, and tensile tests showed improvements in Young's modulus, ultimate tensile strength, and toughness, especially at high strain rates. The nanocomposite containing 20 wt% filler exhibited the highest mechanical performance, suggesting optimal dispersion, interfacial adhesion, and load transfer. These results indicate the strong potential of Bi 2 O 3 ‐CuO nanofillers in engineering PP‐based composites with superior structural and functional properties.