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Graphene in coatings : overcoming the challenges to reap the benefits in COATINGS TECH, Vol. 17, N° 10 (10/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 10 (10/2020) . - p. 14-16 Titre : Graphene in coatings : overcoming the challenges to reap the benefits Type de document : texte imprimé Année de publication : 2020 Article en page(s) : p. 14-16 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Graphène Le graphène est un cristal bidimensionnel (monoplan) de carbone dont l'empilement constitue le graphite. Il a été isolé en 2004 par Andre Geim, du département de physique de l'université de Manchester, qui a reçu pour cette découverte le prix Nobel de physique en 2010 avec Konstantin Novoselov. Il peut être produit de deux manières : par extraction mécanique du graphite (graphène exfolié) dont la technique a été mise au point en 2004, ou par chauffage d'un cristal de carbure de silicium, qui permet la libération des atomes de silicium (graphène epitaxié). Record en conduction thermique jusqu'à 5300 W.m-1.K-1. C'est aussi un matériaux conducteur. Revêtements Index. décimale : 667.9 Revêtements et enduits Résumé : Although graphene comprises a one-atom-thick layer of carbon atoms in its ultimate form to nanoplatelets with multiple morphologies, the arrangement of the carbon atoms in that layered material imparts incredible strength as well as the ability to efficiently conduct heat and electricity in a transparent system with unique optical properties. Not surprisingly, interest in graphene has been high since its discovery in 2004, and significant progress has been made in developing commercially viable production methods and applications. According to a June Graphene Commercialization Update by The Graphene Council,1 over 2,300 graphene-related patents have been granted, mostly to companies and academic institutions, and graphene is predicted to impact more than 45 industry sectors and applications, with the top areas including energy storage, semiconductors, composites/plastics/polymers, advanced materials, metals, chemicals, display electronics, bulk manufacturing, sensors, and healthcare. Notably, the graphene market is maturing, with mainstream companies becoming increasingly involved and a greater percentage of patents relating to higher-value applications rather than graphene production. Several companies are now able to produce up to tons of graphene with batch-to-batch repeatability, with chemical vapor deposition allowing larger formats and quantities at lower prices. Sourcing of raw materials has expanded from graphite mining to include by-products of bio-diesel production and other organic sources such as hemp. Concerns about the safety of graphene are also being addressed, enabling wider adoption of this unusual material. En ligne : https://drive.google.com/file/d/1LiKJtj-BMdbcg6AQwNcK-hJoQ7CzyHly/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34724 [article]

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Coatings mechanics to defend against the environmental elements / Nicholas Foley in COATINGS TECH, Vol. 17, N° 10 (10/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 10 (10/2020) . - p. 18-27 Titre : Coatings mechanics to defend against the environmental elements Type de document : texte imprimé Auteurs : Nicholas Foley, Auteur ; Xin Li, Auteur ; Jack Johnson, Auteur Année de publication : 2020 Article en page(s) : p. 18-27 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Applications extérieures Essais d'adhésion Essais dynamiques Résistance à l'allongement Résistance à la fissuration Résistance à la traction Résistance thermique Revêtements -- Détérioration:Peinture -- Détérioration Revêtements -- Effets du climat:Peinture -- Effets du climat Revêtements -- Effets de la température:Peinture -- Effets de la température Revêtements -- Fissuration:Peinture -- Fissuration Statistique Test d'immersion Index. décimale : 667.9 Revêtements et enduits Résumé : Exterior surfaces experience degradative environmental conditions, such as intense UV exposure, rain, and temperature swings, leading to deterioration. Coatings are low-cost solutions offering decades of protection and preventing significant repair costs for buildings. The coating must withstand UV, mitigate water damage, and express the flexibility required to maintain adhesion to dimensionally unstable substrates (i.e., wood) as they undergo thermal expansion and contraction through the days and seasons. we investigated paint film mechanics through accelerated thermal cycling grain crack and tensile testing with intent to correlate the film properties to exterior exposure data. In this article, we demonstrate that adhesion after accelerated weathering, combined with tensile elongation testing, can be used to model outdoor weathering. Note de contenu : - EXPERIMENTAL SETUP : Adhesion testing - Accelerated thermal cycling grain crack test - Exterior exposure - Tensile elongation testing - Tensile elongation testing variables - Statistical data analysis - RESULTS AND DISCUSSION : Exposure series - Freeze/thaw/immersion cycle accelerated testing - Tensile strength and elongation testing at room temperature - tensile strength and elongation testing at low temperature - Tensile strength and elongation testing after accelerated weathering - Adhesion after water conditioning - Developing new methods to predict grain cracking - Table 1 : The full set of 17 paints comprising this study - Table 2 : Comparative thermal cycling conditions - Table 3 : Significant factors for grain cracking in MLR fitting - Fig. 1 : Pine wood section with labels "s" for late wood and "f" for early wood annular rings - Fig. 2 : Comparative width changes for both early and late annular rings. Negative values indicate contraction and positive values indicate expansion - Fig. 3 : Image of cracking rating standard considered in ASTM D611. Originally from the pictorial photographic reference standards contained in the publication Pictorial Standards of Coatings Defects as published by the Federation of Societies for Coatings Technology - Fig. 4 : Grain cracking rating after four years of exposure vs room-temperature strain at break - Fig. 5 : Grain cracking rating after four years of exposure vs 0°C strain at break - Fig. 6 : Grain cracking rating after 4 years exposure vs -20°C strain at break - Fig. 7 : Grain cracking rating after 4 years exposure vs strain at break after seven day QUV - Fig. 8 : Grain cracking rating after four years of exposure vs strain at brak after seven days in the fog box - Fig. 9 : Grain cracking rating after four years of exposure vs adhesion after seven days fog box - Fig. 10 : Coefficients for grain cracking rating in ML model (scaled and centered). A positive coefficient means that as the independent variable increases, the grain crack rating increases. Conversely, a negative coefficient means that the grain crack rating decreases for a given independent variable - Fig. 11 : Observed vs predicted grain cracking rating in MLR model - Fig. 12 : Room temperature strain at breat, after seven days QUV vs fresh sample En ligne : https://drive.google.com/file/d/1k51AsqqgkIemn1paKlRMn5Q-1fYxOAeY/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34725 [article]

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Particle size distribution, measurement, and assessment : principles, features, limitations, and benefits / Theodore Provder in COATINGS TECH, Vol. 17, N° 10 (10/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 10 (10/2020) . - p. 28-37 Titre : Particle size distribution, measurement, and assessment : principles, features, limitations, and benefits Type de document : texte imprimé Auteurs : Theodore Provder, Auteur Année de publication : 2020 Article en page(s) : p. 28-37 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Chimie analytique Chromatographie Evaluation Granulométrie Mesure Sédimentation Séparation (technologie) Taille des particules Index. décimale : 667.9 Revêtements et enduits Résumé : The field of particle size distribution (PSD) characterization and measurement has experienced a renaissance over the past 40 years. These changes have been driven by advances in electronics, computer technology, and sensor technology in conjunction with the market pull for PSD methods embodied in cost-effective, user-friendly instrumentation. These changes can be characterized by at least four activities: (1) End user innovation exemplified by techniques such as hydrodynamic chromatography (HDC), capillary hydrodynamic fractionation (CHDF), and field flow fractionation methods (sedimentation, flow, and thermal fields, respectively SdFFF, FIFFF, and ThFFF); (2) Revitalization of older instrumental methods such as gravitational and centrifugal sedimentation; (3) Evolution of research-grade instrumentation into low-cost, routine, user-friendly instrumentation exemplified by dynamic light scattering (DLS); and (4) The attempt to meet extremely difficult technical challenges such as: (a) providing a single hybrid instrument with high resolution over a very broad dynamic range (4+ decades in size; e.g., Fraunhofer/Mie; photozone sensing/DLS); (b) PSD measurement of concentrated dispersions (acoustophoretic, dielectric measurements, fiber optic DLS (FOQELS); (c) in-situ process particle size sensors (in-line or at-line, e.g., FOQELS); (d) routine measurement of particle shape and structure (e.g., image analysis). Instrumental methods resulting from these activities are discussed in terms of measurement principles and the strengths and weaknesses of these methods for characterizing PSDs. Business and societal driving forces will impact customer perceived instrumentation and knowledge needs for the future and the ability to meet the specific difficult technical challenges in particle size distribution characterization mentioned above. Anticipated progress toward meeting these technical challenges in particle size distribution characterization mentioned above is discussed. Note de contenu : - END USER INNOVATION - COMMERCIAL DEVELOPMENT : Hydrodynamic Chromatography (HDC) - Capillary Hydrodynamic Fractionation (CHDF) - Field Flow Fractionation (FFF) - REVITALIZATION OF OLDER INSTRUMENTAL METHODS : Gravitational and centrifugal sedimentation - EVOLUTION OF A RESEARCH INSTRUMENT INTO A ROUTINE USER-FRIENDLY INSTRUMENT : Dynamic Light Scattering (DLS, PCS, QELS) - ATTEMPTS TO MEET EXTREMELY DIFFICULT TECHNICAL CHALLENGES - Fig. 1 : Schematic of hydrodynamic chromatography separation mechanism and operative forces - Fig. 2 : Features, benefits, and limitations of hydrodynamic chromatography for PSD analysis - Fig. 3 : Operational factors and data analysis considerations influencing CHDF PSD analysis - Fig. 4 : Features, benefits, and limitations of CHDF for PSD characterization - Fig. 5 : Schematic of FFF instrumentation, separation mechanisms, and channel configurations for SdFFF, FIFFF - Fig. 6 : FFF separation of mixtures of monodisperse latex beads. a) Field programmed SdFFF with rpm = 10 000 at t = 0. b) FIFFF with polypropylene membrane at 42.9 ml/min. c) ThFFF in acetonitrile with ΔT = 170°C. d) StFFF at 38 ml/min and 11000 rpm - Fig. 7 : Features, benefits, and limitations of FFF (SdFFF, FIFFF, ThFFF, and StFFF) for PSD characterization - Fig. 8 : Variations in sedimentation instrumentation and operational factors - Fig. 9 : Equations of motion and stockes' law for gravitational and centrifugal sedimentation - Fig. 10 : Line start separation of a nine-component mixture of polystyrene latex standards (107, 298, 496, 597, 707, 895, 993 µm) - Fig. 11 : Features, benefits, and limitations of sedimentation methods for PSD characterizaton - Fig. 12 : Simplified representation of scattering intensity l(t) and corresponding autocorrelation function C(t) - Fig. 13 : Schematic diagram of a DLS particle sizinginstrument, including autodilution (NICOMP Mdel 370) - Fig. 14 : Features, benefits, and limitations of DLS for PSD characterization - Fig. 15 : Schematic diagram of the auto-dilution apparatus and optical particle sensor (light blockage) - Fig. 16 : Separation of a hexamodal mixture of monodisperse particle size standards by SPOS - Fig. 17 : Combined SPOS/DLS particle size distribution En ligne : https://drive.google.com/file/d/1LTtdDl7x5D9xMy9rTSzO4qY_ql2VpsY1/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34726 [article]

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Coatings Tech Vol. 17, N° 10 URL