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Matériaux fonctionnels carbonés
(56) Production(s) de l'année 2018
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Kinetic regimes in the curing process of epoxy-phenol composites
Auteur(s): Granado Lérys, Kempa Stefan, Gregoriades Laurence, Brüning Frank, Genix A.-C., Fréty Nicole, Anglaret E.
(Article) Publié:
Thermochimica Acta, vol. 667 p.185 - 192 (2018)
Ref HAL: hal-01881804_v1
DOI: 10.1016/j.tca.2018.07.019
WoS: 000444663600024
Exporter : BibTex | endNote
9 Citations
Résumé: Despite an abundant literature on epoxy-amine systems, a complete description of the curing kinetics in epoxy-phenol composites was still lacking. In this study, the curing kinetics of an epoxy-phenol composite relevant to microelectronics industry is probed by isothermal and non-isothermal differential scanning calorimetry. An isoconversional analysis of the data reveals a significant contribution of the diffusion of molecular species to the activation energy, at low temperature and high degrees of curing. A model-fitting of the kinetics is performed in two successive steps: high-temperatures data are fitted with Arrhenius law and nth order autocatalytic model (where the diffusion contribution is neglected), whereas low-temperature data are fitted using Rabinowitch and modified-Williams-Landel-Ferry models (considering a diffusion contribution related to the glass transition). The chemical and diffusion contributions to the rate constants are calculated at various temperatures, clarifying the kinetics regimes with precision. Finally, the kinetics regimes are summarized in an improved time-temperature-transformation diagram.
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Carbon nanotubes functionalized with copper Hexacyanoferrate nanoparticles for a selective extraction of cesium from liquid waste
Auteur(s): Draouil H, Alvarez L., Causse Jérémy, Flaud V., Zaïbi M, Bantignies J.-L., Oueslati M, Cambedouzou J.
(Article) Publié:
Materials And Devices, vol. 3 #2 p.0407 (2018) (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01845473_v1
DOI: 10.23647/ca.md20180407
Exporter : BibTex | endNote
Résumé: Single-walled carbon nanotubes are functionalized with copper hexacyanoferrate nanoparticles for the liquid-solid extraction of cesium from liquid waste and contaminated water. The functionalization process is followed mainly by x-ray photoemission spectroscopy. Indeed, determining the chemical environment around carbon or nitrogen atoms allows to evidence the formation of covalent bounding. In addition, the signatures of iron and copper ions give information on the effective growth of hexacyanoferrate nanoparticles. Furthermore, the cesium sorption mechanism is investigated by comparing the peak intensities associated to the response of potassium and cesium ions. Finally, based on the liquid chromatography analyzes, the sorption of cesium with the functionalized carbon supports is studied. The main results of this work are the demonstration of both a good selectivity of cesium trapping and a high sorption capacity by hybrid single-walled carbon nanotubes.
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Role of charge regulation and flow slip in the ionic conductance of nanopores: An analytical approach
Auteur(s): Manghi Manoel, Palmeri J., Yazda K., Henn F., Jourdain V.
(Article) Publié:
Physical Review E, vol. 98 p.012605 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01844602_v1
Ref Arxiv: 1712.01055
DOI: 10.1103/PhysRevE.98.012605
WoS: 000439065200005
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
6 Citations
Résumé: The number of precise conductance measurements in nanopores is quickly growing. To clarify the dominant mechanisms at play and facilitate the characterization of such systems for which there is still no clear consensus, we propose an analytical approach to the ionic conductance in nanopores that takes into account (i) electro-osmotic effects, (ii) flow slip at the pore surface for hydrophobic nanopores, (iii) a component of the surface charge density that is modulated by the reservoir pH and salt concentration cs using a simple charge regulation model, and (iv) a fixed surface charge density that is unaffected by pH and cs . Limiting cases are explored for various ranges of salt concentration and our formula is used to fit conductance experiments found in the literature for carbon nanotubes. This approach permits us to catalog the different possible transport regimes and propose an explanation for the wide variety of currently known experimental behavior for the conductance versus cs .
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Fonctionnalisation de Nanotubes de Carbone avec des Nanoparticules d’Hexaferrocyanures de Cuivre pour l’extraction sélective de césium
Auteur(s): Alvarez L.
Conference: ELESPEC 2018 (Biarritz, FR, 2018-06-05)
Ref HAL: hal-01829525_v1
Exporter : BibTex | endNote
Résumé: Les nanotubes de carbone monofeuilltes (SWCNT) sont fonctionnalisés avec des nanoparticules d'hexacyanoferrate de cuivre (CuHCF) pour préparer des substrats solides pour la sorption des ions de césium (Cs +) des écoulements de liquide. La haute résistance mécanique et la grande conductivité électrique des SWCNT sont associées à la capacité des nanoparticules de CuHCF à complexer sélectivement les ions Cs + afin de réaliser des buckypapers de type membrane présentant une capacité de charge élevée du césium. Les matériaux sont soigneusement caractérisés en utilisant la microscopie électronique, la diffusion Raman, la spectroscopie de photoélectrons X et les analyses thermogravimétriques. Les isothermes de sorption de Cs sont portées après avoir mesuré la concentration en Cs + par chromatographie ionique en phase liquide dans la solution avant et après l'exposition aux matériaux. On trouve que la capacité totale de sorption du matériau atteint 230 mg.g-1, et qu'environ un tiers du Cs sorbé (80 mg.g-1) est sélectivement complexé dans les nanoparticules de CuHCF greffées sur SWCNTs. Les valeurs ouvrent des perspectives intéressantes dans l'intégration de tels matériaux dans des dispositifs de sorption et de désorption contrôlée de ces ions.
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Carbon nanotubes functionalized with copper hexacyanoferrate nanoparticles for a selective extraction of cesium from nuclear waste
Auteur(s): Alvarez L.
Conference: Chemontubes (Biarritz, FR, 2018-04-22)
Ref HAL: hal-01829522_v1
Exporter : BibTex | endNote
Résumé: Single-walled carbon nanotubes (SWCNTs) are functionalized with copper hexacyanoferrate (CuHCF) nanoparticles to prepare solid substrates for the sorption of cesium ions (Cs+) from liquid outflows. The high mechanical resistance and large electrical conductivity of SWCNTs are associated to the ability of CuHCF nanoparticles to selectively complex Cs+ ions in order to achieve membrane-like buckypapers presenting high loading capacity of cesium. The materials are thoroughly characterized using electron microscopy, Raman scattering, X-ray photoelectron spectroscopy and thermogravimetric analyses. Cs sorption isotherms are plotted after having measured the Cs+ concentration by liquid phase ionic chromatography in the solution before and after exposure to the materials. It is found that the total sorption capacity of the material reaches 230 mg.g-1, and that about one third of the sorbed Cs (80 mg.g-1) is selectively complexed in the CuHCF nanoparticles grafted on SWCNTs.1 These high values open interesting outlooks in the integration of such materials in devices for the controlled sorption and desorption of these ions.
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Local vibrational and mechanical characterization of Ag conducting chalcogenide glasses
Auteur(s): Piarristeguy A., Le Parc R., Ramonda M., Escalier R., Grillo I., Cuello G.J., Cristiglio V., Pradel A.
(Article) Publié:
Journal Of Alloys And Compounds, vol. 762 p.906 - 914 (2018)
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Intralayer and interlayer electron-phonon interactions in twisted graphene heterostructures
Auteur(s): Eliel G. S. N., Moutinho M. V. O., Gadelha A. C., Righi A., Campos L. C., Ribeiro H. B., Chiu Po-Wen, Watanabe K., Taniguchi T., Puech Pascal, Paillet M., Michel T., Venezuela P., Pimenta M. A.
(Article) Publié:
Nature Communications, vol. 9 p.1221 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01793669_v1
DOI: 10.1038/s41467-018-03479-3
WoS: WOS:000428165400020
Exporter : BibTex | endNote
29 Citations
Résumé: The understanding of interactions between electrons and phonons in atomically thin heterostructures is crucial for the engineering of novel two-dimensional devices. Electron–phonon (el–ph) interactions in layered materials can occur involving electrons in the same layer or in different layers. Here we report on the possibility of distinguishing intralayer and interlayer el–ph interactions in samples of twisted bilayer graphene and of probing the intralayer process in graphene/h-BN by using Raman spectroscopy. In the intralayer process, the el–ph scattering occurs in a single graphene layer and the other layer (graphene or h-BN) imposes a periodic potential that backscatters the excited electron, whereas for the interlayer process the el–ph scattering occurs between states in the Dirac cones of adjacent graphene layers. Our methodology of using Raman spectroscopy to probe different types of el–ph interactions can be extended to study any kind of graphene-based heterostructure.
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