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Towards a comprehensive understanding of dirt pickup resistance / Scott C. Brown in COATINGS TECH, Vol. 17, N° 6 (06/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 6 (06/2020) . - p. 14-27 Titre : Towards a comprehensive understanding of dirt pickup resistance Type de document : texte imprimé Auteurs : Scott C. Brown, Auteur ; Michael P. Diebold, Auteur ; Daniel C. Kraiter, Auteur ; Carlos Velez, Auteur ; Peter Jernakoff, Auteur Année de publication : 2020 Article en page(s) : p. 14-27 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Applications extérieures Encrassement Essais accélérés (technologie) Evaluation Revêtements:Peinture Surfaces (technologie) Index. décimale : 667.9 Revêtements et enduits Résumé : The fouling of exterior coating surfaces by dirt is no simple matter. The process is complex, dynamic, and varies in length and time. It also includes a range of confounding particle transport, attachment, and release mechanisms. While complex, strategic, multiscale testing and analysis combined with particle and surface science fundamentals can be used to isolate the dominant mechanisms. In this article, fundamental concepts in surface and particle science as they relate to dirt pickup resistance are presented. We demonstrate how these concepts were applied to develop a failure-mode-targeted accelerated test method resulting in good correlations with outdoor exposure data. We further examine the impact of microscale and nanoscale surface features on the fouling mechanism through direct surface interaction measurements and imaging on commercial coating surfaces. A path forward towards development of a comprehensive, yet practical understanding of dirt pickup resistance is proposed. Note de contenu : - MECHANISMS OF DIRT PICKUP : Deposition - Adhesions and entrenchment - Particle shedding and release - EXPERIMENTAL : Materials (dirt simulants - Paint panels - Commercial paints) - Methods (Outdoor exposure testing - Aerosolized carbon black deposition - Grayscale evaluation - Dirt simulant deposition evaluation - Evaluation of precipitation/water-induced surface creep - Particle shedding assessment of films deposited by aerosol En ligne : https://drive.google.com/file/d/15csF7rv71WGpV8AR9JT9E02zoHXOmqbd/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34356 [article]

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Morphological changes in exterior surface coatings after exposure to cyclic water submersion and ultraviolet exposure / Armin B. Burghart in COATINGS TECH, Vol. 17, N° 6 (06/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 6 (06/2020) . - p. 28-35 Titre : Morphological changes in exterior surface coatings after exposure to cyclic water submersion and ultraviolet exposure Type de document : texte imprimé Auteurs : Armin B. Burghart, Auteur ; Sridhar G. Lyer, Auteur ; William J. Rosano, Auteur Année de publication : 2020 Article en page(s) : p. 28-35 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Immersion Morphologie (matériaux) Revêtements -- Analyse:Peinture -- Analyse Revêtements -- Défauts:Peinture -- Défauts Revêtements -- Effets du rayonnement ultraviolet:Peinture -- Effets du rayonnement ultraviolet Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : Exterior surface coatings used in many applications can be exposed for long periods of time to cyclic exposure consisting of water submersion or local water surface puddling followed by water evaporation and solar exposure. Under such conditions, several macroscopic defects can appear including blistering, adhesion loss, soil pick-up, cracking, erosion, etc. However, quite often surface microscopic film defects can start long before these macroscopic defects are visibly evident. In this article, we show surface microscopic morphology changes to coatings cycled between water (submersion) and ultraviolet (UV) exposure where both polymer and formulation compositional factors were explored. Scanning electron microscopy (SEM) showed microscopic defects such as polymer-filler separation, filler removal, and degradation and crack formation appearance after short-term (one month) cyclic testing. The micrographs also revealed that the observed film defects were confined to the exposed surface and about a few filler particle diameters deep. Note de contenu : - Table 1 : Flexible roof coating screening formulation En ligne : https://drive.google.com/file/d/1RvyZQrUAznRtADhgH9ZZNGQocJdedeRU/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34357 [article]

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The use of engineered silica to enhance coatings / Jim Reader in COATINGS TECH, Vol. 17, N° 6 (06/2020)  

[article]  inCOATINGS TECH > Vol. 17, N° 6 (06/2020) . - p. 36-45 Titre : The use of engineered silica to enhance coatings Type de document : texte imprimé Auteurs : Jim Reader, Auteur ; Maria Nargiello, Auteur Année de publication : 2020 Article en page(s) : p. 36-45 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Anticorrosifs Anticorrosion Brillance (optique) -- Mesure Charges (matériaux) Déperlance Dispersions et suspensions Fluidisation Formation de film Imperméabilisation Matériaux amorphes Mouillabilité Résistance à l'abrasion Rhéologie Silice La silice est la forme naturelle du dioxyde de silicium (SiO2) qui entre dans la composition de nombreux minéraux. La silice existe à l'état libre sous différentes formes cristallines ou amorphes et à l'état combiné dans les silicates, les groupes SiO2 étant alors liés à d'autres atomes (Al : Aluminium, Fe : Fer, Mg : Magnésium, Ca : Calcium, Na : Sodium, K : Potassium...). Les silicates sont les constituants principaux du manteau et de l'écorce terrestre. La silice libre est également très abondante dans la nature, sous forme de quartz, de calcédoine et de terre de diatomée. La silice représente 60,6 % de la masse de la croûte terrestre continentale. Viscosité Index. décimale : 667.9 Revêtements et enduits Résumé : The field of coatings technology has utilized many forms of silica-based particles in the last 70 years. This large, varied class of fillers is generically broken into two categories of crystalline and amorphous morphology. With ongoing scrutiny and sensitivity in the coatings industry to move towards less hazards in the workplace, greater emphasis is placed on suitable amorphous technology to replace crystalline silica technology. Amorphous silica is highly adaptable and flexible to be modified in both powder and pre-dispersed forms, and numerous engineered types of technologies have been developed to provide functional solutions to many coatings problems. Amorphous silica technology has been developed to address functionalities including: rheological control, suspension of pigments and fillers, and reinforcement of coatings film; to impart scratch resistance, hydrophobicity / anti-corrosion benefits, and oleophobicity; as a carrier of trace actives into coatings for homogenous distribution; for flow control, charge, and fluidization enhancement of powdered coatings; and gloss reduction of liquid systems. Particle technology and modification will be addressed along with performance attributes highlighted for each of the types of tailor-made modifications. The importance of proper dispersion and homogenous distribution within a coating matrix will be reviewed. This article will address how amorphous silica technology is differentiated and engineered to create specially tailored solutions to enhance the performance of coatings and will highlight the latest technical developments in this field. Note de contenu : - Rheology and film formation - Anti-corrosion/water repellency - Scratch resistance - Free flow, fluidization, transfer efficiency - Gloss control - Recent developments in silica technology - Fig. 1 : The silica family tree - Fig. 2 : Production of pyrogenic (fumed) silica - Fig. 3 : Primary, secondary, and tertiary structures of fumed silicas - Fig. 4 : Methanol wettability of differently treated fumed silicas - Fig. 5 : Thickening efficiency of fumed silica as a function of surface treatment - Fig. 6 : Improved film formation with fumed silica dispersions - Fig. 7 : Improved corrosion resistance with hydrohobically treated fumed silica ; coatings based on published guide formulations from Halox - Fig. 8 : Structure modification of fumed silica and scratch resistance - Fig. 9 : Homogeneous distribution of silica through a polymer matrix - Fig. 10 : Improved scratch resistance results in a high-soilds, 2K polyurethane clear coat based on Macrymal SM 510n60LG and Vestanat HB 2640MX - Fig. 11 : Transfer efficiency and Faraday cage effects - Fig. 12 : Fluidization efficiency - Fig. 13 & 14 : Measuring gloss with a reflectometer (DIN EN ISO 2813) - Fig. 15 : SEM images of a new spherical precipitated silica particles - Fig. 16 : Viscosity "jump curves" for waterbased silica dispersions - Table 1 : Comparison of characteristics of different synthetic silicas - Table 2 : Common surface treatments for fumed silicas En ligne : https://drive.google.com/file/d/17TVd7hca18xX6Tv0Yq4-_5oKHwAWTdO8/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34358 [article]

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Coatings Tech Vol. 17, N° 6 URL