This study is focused on investigating the role of bismuth oxide (Bi₂O₃) nanoparticles to improve structural, optical, electrical, and mechanical properties of low‐density polyethylene (LDPE). For this purpose, Bi₂O₃ nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x‐ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE‐based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n‐Bi₂O₃ composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n‐Bi₂O₃ composite. In this context, the LDPE/0.5% n‐Bi₂O₃ composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE‐based nanocomposite with better properties for industrial purposes.

In this study, it is aimed to produce a non‐carcinogenic and environmentally friendly biodegradable multi‐functional PVA‐based nanocomposite by improving its electrical properties and mechanical strength. For this purpose, BaO nanoparticles produced by the co‐precipitation method, have been added to the PVA matrix between 0.5% and 5% by mass, and thick film nanocomposites have been produced. The structural properties of the samples and the doping particle have been investigated by FTIR, SEM, and XRD. While electrical measurements have been carried out by an impedance analyzer at room temperature between 20 Hz and 15 MHz frequency, tensile tests have been performed by a mechanical tensile device. The addition of 5% BaO nanoparticles not only increased the energy storage capability of PVA significantly (117%) but also managed to reduce the loss factor considerably (77%). Moreover, compared to other samples, PVA/5% BaO nanocomposite also stands out with its higher ac conductivity within the mid‐and high‐frequency range. Furthermore, the 5% BaO nanoparticle additive provided a serious benefit to the mechanical strength of PVA by improving its Young's modulus, toughness, and stress at the break at different rates. As a result, the BaO nanoparticle additive makes PVA a more functional material as well as more technologically desired.