Experimental and Numerical Investigations of Carbon-based Nanoparticle Reinforcement on Microstructure and Mechanical Properties of Epoxy Coatings

The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings, utilizing their unique characteristics as well as extraordinary mechanical, thermal, and electrical properties. The exceptionally high surface-to-volume ratio of nanoparticles imparts remarkable reinforcing potentials, yet it simultaneously gives rise to a prevalent tendency for nanoparticles to agglomerate into clusters within nanocomposites. The agglomeration behavior of the nanoparticles is predominantly influenced by their distinct microstructures and varied weight concentrations. This study investigated the synergistic effects of nanoparticle geometric shape and weight concentration on the dispersion characteristics of nanoparticles and the physical-mechanical performances of nano-reinforced epoxy coatings. Three carbon-based nanoparticles, nanodiamonds (NDs), carbon nanotubes (CNTs), and graphenes (GNPs), were incorporated into epoxy coatings at three weight concentrations (0.5%, 1.0%, and 2.0%). The experimental findings reveal that epoxy coatings reinforced with NDs demonstrated the most homogenous dispersion characteristics, lowest viscosity, and reduced porosity among all the nanoparticles, which could be attributed to the spherical geometry shape. Due to the superior physical properties, ND-reinforced nanocomposites displayed the highest abrasion resistance and tensile properties. Specifically, the 1.0wt% ND-reinforced nanocomposites exhibited 60%, 52%, and 97% improvements in mass lost, tensile strength, and failure strain, respectively, compared to pure epoxy. Furthermore, the representative volume element (RVE) modeling was employed to validate the experimental results, while highlighting the critical role of nanoparticle agglomeration, orientation, and the presence of voids on the mechanical properties of the nanocomposites. Nano-reinforced epoxy coatings with enhanced mechanical properties are well-suited for application in protective coatings for pipelines, industrial equipment, and automotive parts, where high wear resistance is essential.