Avaliação de nanoplaquetas de grafeno modificadas para incorporação em um revestimento pó base epóxi

Abstract

Nanotechnology has promoted significant advances in the development of nanostructured coatings, replacing conventional fillers with nanofillers, such as graphene nanoplatelets (GNP). Depending on the characteristics and how they are incorporated, GNP can offer thermal and electrical conductivity, mechanical strength, and effective barrier properties against corrosion. In the context of polymeric coatings, especially epoxy-based, the incorporation of GNP can increase chemical resistance, hinder the diffusion of oxygen and aggressive ions, improve the durability and thermal stability of coatings. To increase the compatibility between the nanofillers and the polymer matrix, the modification of GNP with oxygenated groups and silane can enhance the barrier properties and thermal stability of coatings. In this work, the processing of the GNP involved the pre-homogenization of the materials, extrusion, grinding and screening of the coatings. The GNP were incorporated into the coatings formulations at different concentrations (0.1 and 0.2% w/w), followed by application on metal substrates treated with zinc phosphate. In the determination of the specific surface area, the GNP presented the following values: GNP (without modification) with 26.86 m²/g; GNPA (modified with oxygenated groups) with 359.00 m²/g; GNPB (modified with silane) with 143.27 m²/g; and GNPC (modified with cerium dioxide) with 66.29 m²/g. These results demonstrate that the modifications in the GNP increase the specific surface area, a potential property to improve dispersion and interaction with the epoxy matrix, positively influencing the properties of the coatings. The results showed that the samples containing GNP (CREP-0.1GNP, CREP-0.2GNP) and their modified variations, reached the 5B adhesion classification, with 0% of area removed, indicating a better adhesion property compared to the coating without NPG (CREP-0). The thermal conductivity analysis showed that the CREP-0.2GNPB sample, with the highest concentration of GNPB, showed a 45% increase in thermal conductivity, compared to the CREP-0 sample. In the evaluation of flexibility, the samples containing GNP resisted deformation without peeling, demonstrating that the presence of GNP maintains the adhesion of the coating under bending conditions. The thermogravimetric analysis revealed that the presence of modified GNP increased the thermal stability of the composites, and the sample containing GNPC showed the lowest mass loss at elevated temperatures. To validate the coatings as a function of the changes in the GNP, thermal, chemical, physical, morphological and mechanical analyses were performed. The results indicate that modified GNP have the potential to enhance epoxy-based powder coatings, offering an alternative for industrial applications that require advantages in terms of coating performance. [resumo fornecido pelo autor]