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Analysis of the various processes downstream cathodic hydrogen charging, I: Diffusion, laboratory permeation and measurement of hydrogen content and diffusion coefficient / Jean-Louis Crolet in MATERIAUX & TECHNIQUES, Vol. 104, N° 2 (2016)
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Titre : Analysis of the various processes downstream cathodic hydrogen charging, I: Diffusion, laboratory permeation and measurement of hydrogen content and diffusion coefficient Type de document : texte imprimé Auteurs : Jean-Louis Crolet, Auteur Année de publication : 2016 Article en page(s) : 17 p. Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Charge d'hydrogène cathodique' 'Coefficient de diffusion' transitoire' 'Laboratoire perméation' 'Teneur en hydrogène' Index. décimale : 620.11 Matériaux (propriétés, résistance) Résumé : The new views of 2000 on cathodic hydrogen charging are introduced in the numerical modelling of the downstream hydrogen diffusion, and this Part I deals with artificial laboratory permeation with electrochemical measurements on a Pd coated exit face. The “true” transients and steady state are thus calculated for the concentration profiles c(x,t) and the permeation flux Jperm, as well as the permeation efficiency Ep. The former nomenclature in term of thin vs thick membranes is indeed altered by high vs low charging fluxes, or high, medium and low, or still better, very high and moderately high, and very low and moderately low. Results are then compared to the historical calculation tools based on the boundary condition of a constant surface concentration c0 at the entry face. These mathematical tools had been developed a long time ago for permeation under gaseous charging, and they are still valid in this case, but since the abandonment of the Bockris mechanism of discharge-recombination, they are basically invalid for the new cathodic charging by direct proton transfer. More generally, it is emphasised how the two charging modes are different for any subsequent transport process, and more will be addressed in Part II. Then, the totally unexpected consequences on the mechanism of sulfide stress cracking (SSC) will be addressed in Parts III and IV. Note de contenu : - INTRODUCTION : The role of time and fortuity - The "old" hydrogen - The "new" hydrogen
- NUMERICAL MODELLING : Diffusion basics - Artificial laboratory permeation - Joined measurement of the hydrogen content co and diffusion coefficient DHRéférence de l'article : 205 DOI : http://dx.doi.org/10.1051/mattech/2016007 En ligne : http://www.mattech-journal.org/articles/mattech/pdf/2016/02/mt150085.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26656
in MATERIAUX & TECHNIQUES > Vol. 104, N° 2 (2016) . - 17 p.[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 18180 - Périodique Bibliothèque principale Documentaires Disponible Building novel functionalities in coatings using supramolecular polymers / Nilesh S. Phalke in PAINTINDIA, Vol. LXIII, N° 9 (09/2013)
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Titre : Building novel functionalities in coatings using supramolecular polymers Type de document : texte imprimé Auteurs : Nilesh S. Phalke, Auteur ; Rajesh M. Shah, Auteur Année de publication : 2013 Article en page(s) : p. 53-62 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Polymères supramoléculaires Les polymères supramoléculaires sont des longues chaînes linéaires formées par assemblage réversible de composés de faible masse molaire. La réversibilité de l'association confère à ces matériaux des propriétés proches, mais complémentaires de celles des polymères classiques. En effet, dans les conditions d'utilisation, un polymère supra-moléculaire est en équilibre avec son monomère. Par conséquent, en modifiant légèrement les conditions expérimentales (solvant, concentration, température, cisaillement...), il est possible d'allonger ou de raccourcir les chaînes supramoléculaires et donc de changer les propriétés (rhéologiques, mécaniques...) du système. Cette particularité constitue un avantage pour de nombreuses applications potentielles, ainsi qu'une difficulté de caractérisation.Tags : 'Polymères supramoléculaires' 'Liaisons hydrogène' 'Revêtement auto-réparant' Hydrogels 'Composés de coordination' 'Métal-Ligand' 'Host-Guest' 'Plug n play' Index. décimale : 668.9 Polymères Résumé : Supramolecular polymers are polymeric arrays of monomer units, held together by reversible and highly directional secondary interactions — that is, noncovalent bonds, such as hydrogen bonds. The resulting materials therefore maintain their polymeric properties in solution. The directions and strengths of the interactions are precisely tuned so that the array of molecules behaves as a polymer. The high reversibility of the non-covalent bonds ensures that supramolecular polymers are always formed under conditions of thermodynamic equilibrium, and hence the lengths of the chains are directly related to the strength of the non-covalent bond, the concentration of the monomer and the temperature.
Conventional polymers have excellent properties as materials, but when they melt they become highly viscous due to the result of entanglement of their macromolecules. High temperatures and pressures are typically required to provide a melt of sufficiently low viscosity for processing, and this limits their applications. But supramolecular polymers combine good material properties with low viscosity melts that are easy to handle. Some supramolecular polymers also have remarkable characteristics unique to their class, such as the ability to self-heal the fractures in their structure as they permit a rapid response to a change in environment, resulting in easily controllable strength and selectivity of noncovalent interactions. This enables the tuning of material properties in terms of strength, reversibility and directionality which can be utilized to build novel functionalities in coatings.
In this review, an attempt is made to illustrate the classification, mechanisms and applications of the versatile chemistry of supramolecular polymers. It also focuses on important concepts such as molecular self-assembly, folding, molecular recognition, host-guest chemistry and mechanically-interlocked molecular architectures exhibited by supramolecular chemistry. Practical applications of supramolecular polymer chemistry in coatings technology such as self-healing materials, thermally responsive materials and polymer blends are also discussed.Note de contenu : - CLASSIFICATION
- SUPRAMOLECULAR POLYMERIZATION MECHANISMS : A. Isodesmic or Multi Stage oOpen Association (MSOA) - B. Ring-chain - C. Cooperative growth or nucleation-elongation - Hydrogen-bonded polymers - Metal-ligand coordination polymers - π-π stacking
- SUPRAMOLECULAR POLYMERIZATION APPROACHES
- APPLICATIONS OF SUPRAMOLECULAR POLYMERS : Self-healing applications in coatings - Oxygen barrier coatings based on supramolecular assembly of melamine - Supramolecular polymeric hydrogels - Phases separation of supramolecular and dynamic block copolymers - Polymer-coated optical sensor offers improved explosives detection - Ink-jet inks - Catalysis and artificial enzymes based on supramolecular scaffolds - Green chemistry
- FUTURE PERSPECTIVESPermalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19675
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Code-barres Cote Support Localisation Section Disponibilité 15622 - Périodique Bibliothèque principale Documentaires Disponible Intermolecular forces in coatings / James Thomas Guthrie in SURFACE COATINGS INTERNATIONAL, Vol. 79, N° 6 (06/1996)
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Titre : Intermolecular forces in coatings Type de document : texte imprimé Auteurs : James Thomas Guthrie, Auteur Année de publication : 1996 Article en page(s) : p. 268-273 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Peinture 'Matériau revêtement' 'Interaction intermoléculaire' Dipôle 'Liaison hydrogène' 'Propriété physique' Fusion 'Température transition vitreuse' 'Masse moléculaire' Plastifiant transition' Index. décimale : 667.9 Revêtements et enduits Résumé : The physical properties of coatings formulations in the liquid state and the solid state directly arise from interactions which exist between the various components of the formulations. In such systems we can envisage, for the liquid state, the solvent, the resin precursor, the film former, the pigment(s), extenders and any/all additives. In the solid state the solvent is removed. The interplay between the remaining species changes. The solvent provides the basis for mobility, opportunities for change and the possibility of closer approaches to homogeneity within the system (or, in certain instances, greater heterogeneity within the system). Note de contenu : - INTRODUCTION : london forces - dipole-dipole forces - interaction forces-polarisability - hydrogen bonding
- INTRAMOLECULAR FORCES AND PHYSICAL PROPERTIES : volatility
- MELTING FEATURES : the glass transition temperature - factors influencing the glass transition temperature - molar mass effects - chain branching effects - chain across linkage - plasticisers - copolymerisation - measurement of transition temperaturesPermalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17050
in SURFACE COATINGS INTERNATIONAL > Vol. 79, N° 6 (06/1996) . - p. 268-273[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 006572 - Périodique Bibliothèque principale Documentaires Disponible