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Östermalm, Sweden

Ecco L.G.,University of Trento | Fedel M.,University of Trento | Ahniyaz A.,SP Chemistry | Deflorian F.,University of Trento
Progress in Organic Coatings | Year: 2014

A study of the anticorrosive properties of an alkyd coating loaded with polyaniline and cerium oxide (CeO2) nanoparticles is presented in this paper. Investigated by means of Electrochemical Impedance Spectroscopy and accelerated salt spray test, the blank alkyd coating has been loaded with PAni, ceria nanoparticles and the combination of both with 1.0 wt.% content. Through the monitoring of open circuit potential, an ennoblement effect was detected for the systems in the presence of a mild solution. Moreover, EIS evolution of the alkyd containing polyaniline revealed a stable performance of the system in the presence of sulphate solution, whereas for those containing ceria nanoparticles a considerable raise in the |Z|0.015 Hz, from 107 to 108 Ω cm2 in the course of 24 h of immersion, an increasing trend of the charge transfer resistance during the equivalent period of exposure was observed. Furthermore, the anticorrosive contribution given by the ceria nanoparticles is supported by the accelerated salt spray test which revealed lower delamination rates. In the case of the alkyd loaded with polyaniline and ceria nanoparticles simultaneously the evidences are less perceived by means of electrochemical analysis, however, from salt spray tests it can be seen that the influence of the mixture is promising at a certain extent. © 2014 Elsevier B.V. Source

Petersen H.,SP Chemistry | Petersen H.,SP Technical Research Institute of Sweden | Jakubowicz I.,SP Chemistry | Jakubowicz I.,SP Technical Research Institute of Sweden | And 4 more authors.
Applied Clay Science | Year: 2015

A new type of organic compound for modifying clay minerals suitable for use in plasticized polyvinyl chloride was selected and studied. The theory of Hansen solubility parameters was used to predict the miscibility between potential organomodifiers and polyvinyl chloride. In a series of systematic experiments using four very different solvents (i.e., water, ethanol, tetrahydrofuran and chloroform) and three different types of Mt (i.e., Mt-Na+, Mt-PGV and Mt-Ca++), the importance of various parameters to the process of clay mineral intercalation was investigated. The effects of each combination were evaluated employing wide-angle X-ray diffraction and thermogravimetry. The results of swelling experiments on clay mineral in various solvents correlated well with the results of a theoretical preliminary study using Hansen solubility parameters. The extent of swelling followed the order H2O>EtOH>THF>chloroform. The d-spacing seemed to be little affected by the type of solvent used in the modification, while the type of Mt used was important to the intercalation results. Organomodification of Mt-Na+ increased the d-spacing by nearly 0.7nm when tributyl citrate was used as a chelating agent. Similar modification of Mt-Ca++ showed an increase of 0.3nm only. Furthermore, thermogravimetry and DTG curves showed significant structural differences between Mt-Na+ and Mt-Ca++. © 2015 Elsevier B.V. Source

Fedel M.,University of Trento | Ahniyaz A.,SP Chemistry | Ecco L.G.,University of Trento | Deflorian F.,University of Trento
Electrochimica Acta | Year: 2014

The paper aims to provide some insight into the fundamental mechanisms for the behavior of cerium oxides nanoparticles as corrosion inhibitors for steel. The work was carried out on mild steel water based dispersions of cerium oxides nanoparticles in presence of both, sulfates and chlorides. Ceria nanoparticles were produced via precipitation of cerium Ce(NO3)3.6H 2O in water, particles of about 70 nm hydrodynamic diameter were obtained. The analysis of the effectiveness of the ceria nanoparticles as corrosion inhibitors was performed by means of electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) versus time measurements. The experimental measurements suggested that cerium oxide affects the electrochemical properties of mild steel surface; they promoted an ennoblement effect and strong modifications in the impedance response. © 2013 Elsevier Ltd. All rights reserved. Source

Booth A.,Sintef | Storseth T.,Sintef | Altin D.,Biotrix | Fornara A.,German Federal Institute for Risk Assessment | And 5 more authors.
Science of the Total Environment | Year: 2015

An aqueous dispersion of poly (acrylic acid)-stabilised cerium oxide (CeO2) nanoparticles (PAA-CeO2) was evaluated for its stability in a range of freshwater ecotoxicity media (MHRW, TG 201 and M7), with and without natural organic matter (NOM). In a 15day dispersion stability study, PAA-CeO2 did not undergo significant aggregation in any media type. Zeta potential varied between media types and was influenced by PAA-CeO2 concentration, but remained constant over 15days. NOM had no influence on PAA-CeO2 aggregation or zeta potential. The ecotoxicity of the PAA-CeO2 dispersion was investigated in 72h algal growth inhibition tests using the freshwater microalgae Pseudokirchneriella subcapitata. PAA-CeO2 EC50 values for growth inhibition (GI; 0.024mg/L) were 2-3 orders of magnitude lower than pristine CeO2 EC50 values reported in the literature. The concentration of dissolved cerium (Ce3+/Ce4+) in PAA-CeO2 exposure suspensions was very low, ranging between 0.5 and 5.6μg/L. Free PAA concentration in the exposure solutions (0.0096-0.0384mg/L) was significantly lower than the EC10 growth inhibition (47.7mg/L) value of pure PAA, indicating that free PAA did not contribute to the observed toxicity. Elemental analysis indicated that up to 38% of the total Cerium becomes directly associated with the algal cells during the 72h exposure. TOF-SIMS analysis of algal cell wall compounds indicated three different modes of action, including a significant oxidative stress response to PAA-CeO2 exposure. In contrast to pristine CeO2 nanoparticles, which rapidly aggregate in standard ecotoxicity media, PAA-stabilised CeO2 nanoparticles remain dispersed and available to water column species. Interaction of PAA with cell wall components, which could be responsible for the observed biomarker alterations, could not be excluded. This study indicates that the increased dispersion stability of PAA-CeO2 leads to an increase in toxicity compared to pristine non-stabilised forms. © 2014 Elsevier B.V. Source

Petersen H.,SP Chemistry | Petersen H.,SP Technical Research Institute of Sweden | Jakubowicz I.,SP Chemistry | Jakubowicz I.,SP Technical Research Institute of Sweden | And 3 more authors.
Journal of Applied Polymer Science | Year: 2016

Montmorillonite (MMT) was organically modified with tributyl citrate (TBC). Organoclays (OMMTs) were processed with diisononyl phthalate (DINP)-plasticized polyvinyl chloride (PVC) to form polymer nanocomposites. The produced composite materials showed a contradictory change in properties to that expected of a layered silicate nanocomposite, with a decreased E-modulus and increased gas permeability compared with a material without OMMT. It was experimentally shown that the TBC modifier was extracted from the OMMT and was dispersed in the PVC/DINP matrix, whereupon the OMMT collapsed and formed micrometer-sized agglomerates. Further investigation revealed that TBC has a significant effect on the gas permeability and the E-modulus, even at low additions to a DINP-plasticized PVC. A PVC nanocomposite with the TBC acting as both the OM for MMT and as the primary plasticizer was produced. This material showed a significantly increased E-modulus as well as a decrease in gas permeability, confirming that it is possible to develop a nanocomposite based on plasticized PVC, if both the organo-modification of the MMT and the formulation of the matrix are carefully selected. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42876. © 2015 Wiley Periodicals, Inc. Source

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