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Hang T.T.X.,Institute for Tropical Technology | Truc T.A.,Institute for Tropical Technology | Olivier M.-G.,University of Mons | Vandermiers C.,University of Mons | And 2 more authors.
Progress in Organic Coatings

This work is an extension of studies into the mechanisms of corrosion protection of mild steel by an epoxy resin containing organically modified clay (Hang et al. [1]; Truc et al. [2]). In a previous study (Truc et al. [2]), it was shown that indole-3 butyric acid (IBA)-modified clay improved the corrosion performance of epoxy. In the present study, it was shown that the IBA is an anodic inhibitor and its efficiency was about 93%. Exfoliation and dispersion of the IBA-modified clay in the epoxy coating were checked by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The improvement of the corrosion performance of the epoxy coating containing IBA-modified clay by comparison with pure epoxy coating was confirmed for a low film thickness (10 μm). Local electrochemical impedance measurements performed on scratched samples revealed the inhibitive action of IBA at the carbon steel/coating interface. It was shown that the inhibitor release from the IBA-modified clay was favoured for high pH values. Thus, in neutral media, the corrosion process which induces a local increase of pH will increase the self-healing performance. © 2010 Elsevier B.V. Source

Nguyen T.V.,Institute for Tropical Technology | Nguyen Tri P.,University of Montreal | Nguyen T.D.,Institute for Tropical Technology | El Aidani R.,ETS | And 2 more authors.
Polymer Degradation and Stability

In this study, the degradation of a water-borne acrylic coating and the influence of rutile-TiO2 (R-TiO2) nanoparticles and a hindered amine light stabilizer (HALS) on its photo-stability in accelerated aging environment has been quantitatively studied by monitoring the chemical modifications occurring upon aging conditions. By using non-destructive analytical methods, like IR and UV-visible spectroscopy, 3D laser microscopy, SEM observations and weight loss measurements, it was possible to follow continuously the formation of photo-oxidative products and the loss of the binder functional groups on a sample undergoing accelerated aging. For the first time, numerous dark spots, randomly dispersed on the whole surface of the sample upon UV/condensation exposure are successfully observed and explained by using a novel technique 3D laser microscopy. Our findings also confirm that HALS greatly improved photo-stability to the coating thank to its free radical and hydrogen peroxide scavenging capacity. This work provides some useful information for a better understanding of the degradation behavior of water-borne acrylic coating under accelerated aging conditions. © 2016 Elsevier Ltd. All rights reserved. Source

Nguyen T.H.,Hanoi National University of Education | Nguyen T.A.,Institute for Tropical Technology | Nguyen T.V.,Institute for Tropical Technology | Le V.K.,Hanoi National University of Education | And 3 more authors.
International Journal of Corrosion

The electrical rehabilitation treatments of repair mortar were performed with tetrabutylammonium bromide salt (TBAB) at an electrical current density of 5 A/m2, using two electrolytes (0.1 M NaOH and 0.1 M Na3BO3 solutions), and for two time periods (1 and 4 weeks), respectively. The average organic cation-based inhibitor's concentration in cement mortars before and after this treatment was quantified using the UV-Vis spectroscopy. The experimental results reveal that the EICI treatment with 0.1 M Na3BO3 was more effective in injecting the inhibitor and in improving the chloride penetration resistance and compressive strength of the mortar, relative to using 0.1 M NaOH as electrolyte. In this case, after the 4-week EICI treatment, [TBA+] contents were 2.3 % and 2.4% by mass of cement mortar for uncontaminated and salt-contaminated mortars, respectively. After the 4-week EICI treatment, the apparent diffusion coefficients of chloride anion in cement mortar were decreased by 40% from 1.52 × 10-10 m2/s. The EICI treatment was able to halt the chloride-induced corrosion of the steel rebar by promoting its passivation. The 2-week EICI treatment using sodium hydroxide and sodium borate solutions decreased the corrosion current density of the rebar by 77.8% and 78.5%, respectively, approximately two months after the treatment. © 2015 The Huyen Nguyen et al. Source

Trinh A.T.,Institute for Tropical Technology | Nguyen T.T.,Institute for Tropical Technology | Thai T.T.,Institute for Tropical Technology | To T.X.H.,Institute for Tropical Technology | And 4 more authors.
Journal of Coatings Technology Research

In this study, synthesized magnetite (Fe3O4) nanoparticles were treated with a corrosion inhibitor, indole-3 butyric acid (IBA) and incorporated in an epoxy-polyamide coating. The coating was applied on a carbon steel substrate. For comparison, coatings without particles or with nontreated Fe3O4 particles were also prepared. The IBA-modified nanomagnetite (IBA–Fe3O4) was characterized by infrared spectroscopy and Zeta potential measurements. The inhibitive action of IBA was shown by electrochemical measurements (polarization curves) performed for a bare carbon steel in 0.1 M NaCl solution containing Fe3O4 or IBA–Fe3O4 nanoparticles. Adherence and anticorrosion properties of the epoxy-based coatings containing Fe3O4 or IBA–Fe3O4 were compared to those of the pure epoxy-polyamide resin by dry and wet adherence measurements and by salt spray test. The results showed significant improvement of the film adherence and higher corrosion protection of the carbon steel in the presence of IBA–Fe3O4. It was concluded that the IBA effect was restricted to the metal/coating interface. © 2016, American Coatings Association. Source

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