The use of conducting polymers as coating layers for the protection of surfaces against corrosion represents an important topic for investigation, as reported in the literature. In this work, polypyrrole/Fe3O4 nanoparticles (Fe3O4_NPs/PPy) hybrid nanocomposites (HN) were incorporated as anticorrosive additives in an epoxy paint to protect SAE 1010 carbon steel from corrosion. The HN particles were obtained by chemical polymerization of pyrrole in an aqueous solution in the presence of Fe3O4_NPs and were characterized by infrared absorption spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM). The electrochemical impedance spectroscopy (EIS) was used in the analysis of the electrochemical response of the coated surface with and without HN. DLS data showed that the Fe3O4_NPs and Fe3O4_NPs/PPy obtained in solution present average diameters of (19.7 ± 9.6) nm and (63.5 ± 27.7) nm, respectively. TEM images showed Fe3O4_NPs with smaller sizes (10 nm - 30 nm), and that the HN had diameters smaller than 100 nm, consisting of Fe3O4 cores coated with polypyrrole. EIS measurements have shown that the addition of HN to the epoxy paint could improve the efficiency of the anticorrosive coating when compared to the original epoxy paint prepared without any corrosion inhibitor.

We synthesized (ZnO nanoparticles)/polypyrrole (ZnO_NPs/PPy) hybrid nanocomposites and used them as additives in an epoxy paint to protect SAE 1020 carbon steel from corrosion. The nanocomposites were obtained by chemical polymerization of pyrrole in aqueous solution and sodium dodecyl sulfate solution containing dispersed ZnO nanoparticles. We characterized the nanoparticles by infrared absorption spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A large disparity in the distribution of ZnO particle sizes became evident from the TEM images, which also show the formation of hybrid nanocomposites consisting of polypyrrole coated ZnO nanoparticles. Electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) tests, which were performed on SAE 1020 carbon steel plates coated with epoxy and ZnO_NPs/PPy, have shown that epoxy paints have their efficiency as anticorrosive coatings significantly improved when ZnO_NPs/PPy hybrid nanocomposites are added to them.

Polímeros expandidos são bastante competitivos para serem utilizados como materiais de flutuabilidade, devido a sua baixa densidade. Em particular, eles se apresentam muito eficientes no desenvolvimento de módulos de flutuabilidade de robôs submarinos do tipo ROV (Remote Operated Vehicle). Este trabalho descreve um estudo da absorção de água em dois diferentes tipos de polímeros expandidos (poliuretano e poliestireno expandido), em diferentes meios aquosos (água do mar e água destilada). Estudo sobre o efeito da geometria das amostras com relação à cinética de absorção de água demonstrou que as amostras com maior área de contato com a água se apresentam mais susceptíveis à absorção de água. Os estudos também revelaram que o poliuretano expandido sofreu uma importante perda de material devido ao seu manuseio durante os ensaios de absorção. A influência do meio aquoso foi também bastante notável para este material, no qual apresentou uma maior taxa de absorção nos ensaios com água destilada em comparação com os ensaios utilizando água do mar. Os resultados das análises demonstraram que o melhor material para ser utilizado como módulo de flutuabilidade do robô submarino é o poliestireno expandido, pois este material não apresentou uma notável degradação e perda de material durante os ensaios de absorção.

Owing to the low density and relative low price, expanded polymers appear to be competitive for buoyancy systems. Expanded polymers are particularly efficient to develop buoyancy modules of submarine robots such as ROV (Remote Operated Vehicle). This work describes water absorption mechanisms of two expanded polymers (expanded polyurethane and expanded polystyrene), in various aqueous media (seawater and distilled water). The influence of the samples geometry on the water absorption kinetics was studied. The samples with a larger contact area with water were found to be more susceptible to water absorption. The analyses also reveal a potential loss of material in the expanded polyurethane due to its manipulation during the absorption tests. The influence of the aqueous media was also significant for this material, which presents a level of absorption in distilled water higher than in seawater. The results of this study justify the selection of the expanded polystyrene, which appears particularly suitable to the development of the buoyancy modules of submarine mini-robots.