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Le Mans, France

El Mendili Y.,University of Nantes | Minisini B.,ISMANS | Abdelouas A.,University of Nantes | Bardeau J.-F.,CNRS Le Mans Institute of Molecules and Materials
RSC Advances | Year: 2014

The mackinawite mineral was prepared as a carbon steel corrosion product in sulfidogenic waters at 90 °C after 2 months. The tetragonal crystal structure of the material was confirmed by Rietveld refinement of X-ray diffraction (XRD) data, and vibrational modes were analysed by micro-Raman spectroscopy. Despite a large number of studies on the formation and the stability of tetragonal mackinawite, the interpretation of the Raman spectra remains uncertain. In the present study, we report on the first calculation of the Raman-active vibrational modes of mackinawite using Density Functional Perturbation Theory and direct methods with BLYP + dispersion correction. Based on the comparison between calculated and experimental results, the four fundamental vibrational modes were assigned as 228 cm-1 (B 1g), 246 cm-1 (Eg), 373 cm-1 (A 1g) and 402 cm-1 (Eg). © the Partner Organisations 2014.

Chivas-Joly C.,French National Laboratory of Metrology and Testing | Motzkus C.,French National Laboratory of Metrology and Testing | Guillaume E.,French National Laboratory of Metrology and Testing | Ducourtieux S.,French National Laboratory of Metrology and Testing | And 6 more authors.
Fire and Materials | Year: 2014

Carbon nanotube-based poly(methyl methacrylate) and polyamide-6 nanocomposites have been investigated using various techniques within the framework of the NANOFEU project. Scanning transmission electron microscopy was used to characterize morphologies of composites, while fire properties were studied using cone calorimeter and pyrolysis combustion flow microcalorimeter. The study focused particularly on composition and microstructure of gaseous and aerosol products. Morphology of ultrafine particles released from the combustion of nanocomposites was studied using cascade impactor and atomic force microscopy. Fire behaviour has been interpreted in relation with the degradation mechanisms specifically induced by the presence of carbon nanotubes. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

Verchery G.,ISMANS
Mechanics of Composite Materials | Year: 2011

This paper aims at promoting laminate designs with specific stiffness properties: quasi-homogeneous, quasi-isotropic quasi-homogeneous, and thermally stable laminates. For this, the paper first discusses the concept of design, reviews the classical laminated plate theory and the usual design rules for laminates, and introduces the polar method for plane anisotropy. Then it develops rules and methods to design the stiffness properties that are looked for. In conclusion, it suggests that the classical design rules are too restrictive and that innovative designs should be explored for a better use of composites. © 2011 Springer Science+Business Media, Inc.

Chauke H.R.,University of Limpopo | Minisini B.,ISMANS | Drautz R.,Ruhr University Bochum | Nguyen-Manh D.,Babcock Power | And 3 more authors.
Intermetallics | Year: 2010

The deleterious low-temperature tetragonal phases in prototypical Pt-based superalloys have variously been reported as taking the tI16-U3Si (DOc), tI16-Ir3Si (DOc′) and tP16-Pt3Ga structure-types in contrast to the high-temperature cubic cP4-Cu3Au (L12) phase. We have investigated the relative stability of these four structure-types at absolute zero by using density functional theory. We find that the ground state of stoichiometric Pt3Al is tP16-Pt3Ga and that the other three lattices are mechanically unstable at absolute zero. Experiments are needed to measure the internal displacement parameters of these three competing tetragonal phases. © 2009 Elsevier Ltd. All rights reserved.

Minisini B.,ISMANS | Vathonne E.,ISMANS | Chivas-Joly C.,French National Laboratory of Metrology and Testing | Lopez-Cuesta J.-M.,Ecole des Mines dAles
Journal of Molecular Modeling | Year: 2013

DFT calculations, with VWN exchange correlation functional and double numeric basis set, were used to evaluate the energies required for the scission reactions taking place in the initial stage of the thermal degradation of Poly(methyl methacrylate) (PMMA) in the presence of a carbon nanotube (CNT). Side group and main chain scissions were investigated. The results averaged from five configurations of pure PMMA (DP = 5) were used as references and compared to the results obtained for the five same configurations of PMMA grafted on three carbon nanotubes of similar diameter (1.49 nm). The bond dissociation energies (BDE) of main chain scission evaluated for grafted PMMA was 4 % less endothermic than for pure PMMA. These results seemed independent of the tested chirality (11,11); (12,10) and (16,5) of the carbon nanotubes. Comparisons with the BDE of the weakest bonds due to intrinsic defaults (head to head and unsaturated end chain) were performed. [Figure not available: see fulltext.] © 2012 Springer-Verlag.

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