Resumo: Neste trabalho avaliou-se a influência do tratamento alcalino das fibras de curauá, nas concentrações de 1, 5 e 10%(m/v) de NaOH, nas propriedades dos compósitos com matriz de PHBV e 20% m/m de fibras de curauá. Os compósitos foram moldados por extrusão e injeção e avaliadas suas as propriedades morfológicas, térmicas e mecânicas. Os resultados de FTIR mostraram que o tratamento alcalino promoveu modificações na estrutura das fibras de curauá, comprovadas pela remoção da hemicelulose e da lignina, evidenciadas pela ausência das bandas típicas destes compostos. Nos compósitos com fibras de curauá tratadas com solução de NaOH na concentração de 5% apresentaram um aumento de 30% na resistência à flexão e 12% na resistência ao impacto, quando comparados aos compósitos com fibras sem tratamento. Estes resultados indicam que o tratamento alcalino promoveu uma melhoria na adesão das fibras na matriz, o que melhorou significativamente as propriedades mecânicas dos compósitos. Palavras-chave: Compósitos, PHBV, fibras de curauá, tratamento alcalino. Effect of the Alkaline Treatments of Curauá Fiber on the Properties of Biodegradable Matrix CompositesAbstract: This study investigate the influence of alkaline treatment applied to Curauá fibers, at concentrations of 1, 5 and 10% (w/v) NaOH, on the properties of the composite of PHBV matrix with 20 wt % Curauá fiber. The composites were molded by extrusion and injection and their morphological, thermal and mechanical properties were evaluated. The results showed that alkali treatment caused modifications in the structure of the Curauá fibers by the removal of hemicellulose and lignin, as evidenced by the absence of the typical bands of these compounds in FTIR analysis. It was found an increase of 30% in flexural strength and 12% in impact resistance for the composites with fibers treated in 5% NaOH solution, in relation to composites with fibers without treatment. These results indicate that the alkaline treatment promoted an improvement in the adhesion of the fibers to the matrix, which significantly improved the mechanical properties of the composites. However, concentrations of NaOH solution different from 5% may have a deleterious effect on the mechanical properties of the fibers and composites.

The use of coatings based on alkoxysilanes is one of the most effective ways to control the release of cytotoxic ions by metal implants. To improve the success rate of titanium–aluminum–vanadium implants, in this study, we evaluated the physicochemical, morphological, mechanical, and electrochemical behavior of hybrid coatings based on alkoxysilanes applied on the alloy. The coatings were prepared with the precursors 3‐(trimethoxysilyl propyl)methacrylate and tetraethoxysilane alkoxides by the sol–gel method. The curing of the coatings was evaluated at different temperatures (90, 180, and 300 °C) for 1 h. We carried out the pretreatment of the alloy by polishing and attacking it with sodium hydroxide. The results indicate that the temperature of 90 °C was effective for solvent evaporation and complete crosslinking of the film, and the alkaline pretreatment allowed the formation of a film with better anticorrosive performance; this indicated that the presence of hydroxyl groups on the surface improved the coating adhesion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45470.

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Tinplate is used to food packaging and other types of packages. The corrosion resistance of the tinplate has been study due the necessity of an alternative to high environmental impact of chromatization process. Therefore protective coatings as hybrid films base elaborations with different acids are studied to improve the barrier effect against corrosion. The objective of this work is characterize hybrid films deposited on a tinplate from a sol made up of the alkoxide precursors 3-(trimethoxysilylpropyl) methacrylate (TMSM), tetraethoxysilane (TEOS) and poly(methyl methacrylate) (PMMA) together with one of three acids (acetic, hydrochloric or nitric acid) and to verify their action against the corrosion of the substrate. The films were obtained by a dip-coating process and cured for 3 hours at 160 °C. The film hydrophobicity was determined by contact angle measurements, and the morphology was evaluated by SEM. FTIR measurements were performed to characterize the chemical structures of the films. The electrochemical behavior of the coatings was evaluated by techniques open circuit potential monitoring (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results demonstrate that the siloxane-PMMA films improve the protective properties of the tinplate, with the films obtained by acetic acid addition exhibiting the greatest improvement.