Development of an accelerated test method for dirt pick-up resistance / Daniel C. Kraiter in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 5 (09/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 5 (09/2021) . - p. 1413-1430 Titre : Development of an accelerated test method for dirt pick-up resistance Type de document : texte imprimé Auteurs : Daniel C. Kraiter, Auteur ; Scott C. Brown, Auteur ; Michael P. Diebold, Auteur ; Peter Jernakoff, Auteur ; Alan F. Vera-Balbuena, Auteur Année de publication : 2021 Article en page(s) : p. 1413-1430 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adhésion thermique Caractérisation Concentration pigmentaire volumique Essais accélérés (technologie) Liants Résistance à la salissure Revêtements en bâtiment:Peinture en bâtiment Transition vitreuse Index. décimale : 667.9 Revêtements et enduits Résumé : Dirt pick-up is a long-standing issue for exterior architectural coatings. Dirt pick-up resistance (DPR) is highly sought by end users, and significant resources have been committed by paint manufacturers to improve it. The task is complicated by the multitude of regional and local factors such as seasonal weather, intensity of economic activity, or atmospheric particle burden. Typically, paint manufacturers try to control DPR via careful selection of additives and formula optimization. Testing the new formulas in real time is long and, therefore, there is a clear need for a faster and more reliable test that takes into account the key elements of the dirt pick-up mechanism: particle transport, adhesion, and release to/from the surface. Our team has developed an accelerated test that focuses on thermally driven adhesion and takes a fraction of the time necessary for outdoor exposure testing. The test correlates well with early outdoor exposure results when formulation parameters are controlled and when there are moderate-to-large performance differences among paint formulas. The test was used to improve the accelerated DPR of a paint formula, which subsequently was verified against real-time outdoor exposure in three geographic regions with different climates and airborne particulate pollution levels. Note de contenu : - Table 1 : Outdoor exposure sites and conditions - Table 2 : Composition and characterization of polymeric binders - Table 3 : Composition of paints having binders with different Tg values - Table 4 : Coefficients of correlation between outdoor exposure (several months) and accelerated test method (using twenty-four dusting events) for the binder Tg series - Table 5 : Composition of paints having different PVCs - Table 6 : Coefficients of correlation between outdoor exposure (several months) and accelerated test method (using twenty-four dusting events) for the PVC series - Table 7 : Commercial paints (and selected properties) used for the comparison of outdoor exposure and accelerated test - Table 8 : Impact of crosslinking on film properties - Table 9 : Paint variables evaluated in the experimental design DOI : https://doi.org/10.1007/s11998-021-00506-9 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00506-9.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36443 [article]

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Effect of exposure conditions on dirt pickup resistance (DPR) / Michael P. Diebold in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 17, N° 3 (05-06/2020)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 17, N° 3 (05-06/2020) . - p. 597–611 Titre : Effect of exposure conditions on dirt pickup resistance (DPR) Type de document : texte imprimé Auteurs : Michael P. Diebold, Auteur ; Daniel C. Kraiter, Auteur Année de publication : 2020 Article en page(s) : p. 597–611 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Champignons microscopiques Décoloration Essais (technologie) Résistance à la salissure Revêtements -- Détérioration:Peinture -- Détérioration Revêtements en bâtiment:Peinture en bâtiment Salissures biologiques Index. décimale : 667.9 Revêtements et enduits Résumé : Discoloration over time is a common cause for dissatisfaction of exterior architectural (décor) paints in much of the world. As such, it is an area of active research interest for producers of these paints and their raw material suppliers. The rate of discoloration of any particular paint depends on the interplay between certain physical properties of that paint and the environmental exposure conditions. Such an interplay can be established by exposing a series of paints to a variety of real-world environmental conditions. In this paper, we report the dirt pickup resistance results for 26 commercial exterior paints exposed at four different locations and the results of a subsequent study of ten commercial paints at two exposure locations. Repeatability and reproducibility of these tests were determined by exposing the same two paints, with replicates, at different exposure sites and at different dates. We believe this is the first time such information has been reported. Within-series repeatability was good, but series-to-series reproducibility was poor, stressing the need to compare performance only among paints exposed at the same time and location. In addition to testing dirt pickup, we investigated the degree to which microbial growth can contribute to discoloration and found a strong correlation between mildew infestation and decrease in L* under conditions that favor mildew growth. Finally, we investigated the extent to which panel orientation affects the decrease in film brightness over time and found that change in L* was partially dependent on orientation, and that early results at 45° south-facing were accurate predictors of long-term results for vertical orientations for the paints tested. Note de contenu : - Results and discussion : Benchmark paints - Exposures at sites with high levels of particulates - Performance of NATP and NACP paints in different exposure series - Mildew resistance - Benchmark paints - Effect of orientation on DPR - Comparative mildew performance of NATP and NACP paints DOI : https://doi.org/10.1007/s11998-020-00340-5 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-020-00340-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34092 [article]

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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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Use of MieLab software in scattering calculations / Daniel C. Kraiter in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 6 (11/2022)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 19, N° 6 (11/2022) . - p. 1817-1836 Titre : Use of MieLab software in scattering calculations Type de document : texte imprimé Auteurs : Daniel C. Kraiter, Auteur ; Michael P. Diebold, Auteur ; Jelena Lasio, Auteur Année de publication : 2022 Article en page(s) : p. 1817-1836 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Coefficient de diffusion Un coefficient de diffusion est une grandeur caractéristique du phénomène de diffusion de la matière. Le coefficient de diffusion mesure le rapport entre le flux molaire dû à la diffusion moléculaire, et le gradient de concentration de l'espèce chimique considérée (ou, plus généralement, de la variable d'effort entraînant cette diffusion), comme formulé par la loi de Fick. Concentration pigmentaire volumique critique Dioxyde de titane Logiciels Matériaux mésoporeux Nanoparticules Ondes électromagnétiques Pigments inorganiques 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. Sphères creuses Index. décimale : 667.9 Revêtements et enduits Résumé : MieLab software was used to perform calculations of the scattering of electromagnetic radiation by single or multilayered spheres. The scattering efficiency results allowed the calculation of scattering coefficients SMie, which were then used to compare the scattering performance of different materials and composites. Furthermore, the simulation results were compared to experimental results obtained from testing real paint films using the Kubelka–Munk treatment for TiO2-only systems (SCoat). It was found that SMie follows the same profile as SCoat in response to the change in pigment volume concentration. The MieLab simulations were also applied to two composite configurations, hollow sphere nanoparticles or mesoporous silica nanoparticles attached to a TiO2 pigmentary size particle. The results showed that neither of these configurations is a viable solution for increasing scattering efficiency of TiO2 in the range of typical PVCs. Note de contenu : - R.I. dependency on wavelength - Impact of particle size on scattering efficiency at fixed wavelength - Scattering of a solid particle in media of different R.I.'s in the visible range - Impact of P.S. distribution on scattering - Impact of particle shell - Impact of PVC on system R.I. and SMie (above and below cPVC) - Impact of oiling the surface on SMie and SCoat - Scattering calculations for TiO2 – hollow sphere nanoparticles and TiO2- mesoporous silica particles model composites - Table 1 : Refractive index as a function of wavelength for some common materials used in scattering applications. Note that the equations are written for λ in micrometers - Table 2 : Properties of the paints made and used in this work - Table 3 : SMie Calculation at constant dry film thickness - Table 4 : SMie Calculation at increasing dry film thickness above the cPVC - Table 5 : Calculation of medium refractive index and total PVC in the TiO2 – hollow sphere nanoparticles composite - Table 6 : Calculation of medium refractive index and total PVC in the TiO2 – mesoporous silica nanoparticles composite DOI : https://doi.org/10.1007/s11998-022-00654-6 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-022-00654-6.pdf?pdf=button Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38500 [article]

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