# The Influence of Copper Oxide Particle Size on the Properties of Epoxy Resin
## 1 Introduction
However, the addition of aluminum oxide particles resulted in an increase in Young's modulus and bending strength with a rise in particle content, up to 10% by weight, and then a decrease [19]. [PERSON] et al. conducted a study to examine the influence of aluminum oxide particle size on the dielectric and mechanical properties of epoxy composites. The study's findings demonstrated that incorporating nanofillers can enhance the breakdown strength and discharge resistance of the dielectric. Conversely, microfillers can result in a decrease in short-term puncture strength with an increase in content, a phenomenon attributed to the emergence of more defects. However, it was observed that the short-term puncture strength of the nanocomposite increased with an increase in the level of nanofiller dispersion [20]. [PERSON] and [PERSON] conducted research to investigate the impact of aluminum oxide on the thermal and dielectric properties of epoxy composites. Specifically, they examined the effect of varying the microparticle content at 4%, 9%, 14%, 21%, 28%, 37%, and 48% volume. The study revealed that the incorporation of aluminum particles had no effect on the thermal stability of the epoxy composites. However, it did reduce the glass transition temperature (Tg). The size, concentration, and surface area of the aluminum particles were found to influence the thermal conductivity and dielectric properties of the composites. The dielectric permittivity increased with an increase in the aluminum particle content. Furthermore, the dielectric permittivity and losses increased with temperature due to the segmental mobility of the polymer molecule [21]. Copper oxide, also known as copper(II) oxide, is a semiconductor compound with a monoclinic structure that has attracted considerable interest due to its status as the simplest member of the copper family and its potential for various physical properties. These properties include high-temperature superconductivity, electron correlation effects, and spin dynamics. CuO is an essential p-type semiconductor with a wide range of applications such as in gas sensors, catalysis, batteries, high-temperature superconductors, solar energy conversion, and field emission emitters. In the realm of energy saving, energy transfer fluids enriched with CuO nanoparticles can improve fluid viscosity and increase thermal conductivity. The narrow band gap of CuO crystal structures endows them with useful photocatalytic, photovoltaic, and photoconductive properties. CuO is also a more economical alternative to silver, miscible with polymers, and relatively stable in terms of chemical and physical properties. Additionally, metal oxide nanoparticles with a high degree of ionization, such as CuO, can be useful as antimicrobial agents due to the possibility of producing them with an extremely large surface area and unusual crystal morphology [22]. Copper oxide nanoparticles are typically available in the form of a brown-black powder. They can be reduced to metallic copper under the influence of hydrogen or carbon monoxide at elevated temperatures. These nanoparticles have diverse applications in fields such as catalysis, gas sensors, magnetic storage media, batteries, solar energy transformers, semiconductors, and field emission. Copper oxide nanoparticles, with their P-type semiconductor properties and narrow band gap, have garnered significant interest for their potential use in electronic, optoelectronic, and sensing nanostructures. They are commonly utilized as effective heterogeneous catalysts, characterized by their high activity and selectivity in oxidation and reduction reactions [23]. Copper oxide also exhibits bactericidal properties, making it suitable for use in food-processing equipment as a means of self-sterilizing the environment and preventing the spread of microorganisms. The increasing cost of silver particles has led to a shift toward using copper as a more cost-effective alternative.