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On the use of the atomic force microscope to monitor physical degradation of polymeric coating surfaces / Mark R. VanLandingham in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 923 (12/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 923 (12/2001) . - p. 43-50 Titre : On the use of the atomic force microscope to monitor physical degradation of polymeric coating surfaces Type de document : texte imprimé Auteurs : Mark R. VanLandingham, Auteur ; Jonathan W. Martin, Auteur ; Eric Byrd, Auteur ; Tinh Nguyen, Auteur Année de publication : 2001 Article en page(s) : p. 43-50 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Essai  vieillissement  accéléré  Mélamine  résine  Acrylique  dérivé  polymère  Microscopie  force  atomique  Dégradation  Feuil  Polymère  Peinture  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : The atomic force microscope (AFM) was used to monitor changes in surface features of an acrylic melamine coating that was exposed to a variety of conditions. Exposure to ultraviolet (UV) radiation and high relative humidity caused general roughening of the surface and the formation of pits. Further, the damage of the coating surface was much more substantial for exposure to high relative humidity compared to exposure to dry environments. This difference in degradation rates correlated with measurements of chemical degradation determined using infrared spectra that were acquired along with the AFM images. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5770 [article]

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UV-visible technique for studying powder coatings and their dissolution / Önder Pekcan in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 923 (12/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 923 (12/2001) . - p. 51-60 Titre : UV-visible technique for studying powder coatings and their dissolution Type de document : texte imprimé Auteurs : Önder Pekcan, Auteur ; Ertan Arda, Auteur Année de publication : 2001 Article en page(s) : p. 51-60 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Spectrométrie  UV  visible  Recuit  Traitement  thermique  Heptane  Chloroforme  Solvant  organique  Dissolution  Méthacrylate  de  méthyle  polymère  Latex  Formation  film  Peinture  poudre  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : UV-Visible (UVV) technique was used to monitor powder coating and its dissolution processes from hard latex particles. Three sets of latex coatings were prepared from poly(methyl methacrylate) (PMMA) particles. The first set of coatings was annealed at elevated temperatures in various time intervals during which reflected photon intensity, Irf, was measured. The second set of coatings was annealed at various temperatures in 10 min time intervals during which transmitted intensity, Itr, was measured. Irf first decreased and then increased as the annealing temperature was increased. Decrease in Irf was explained with the void closure mechanism due to viscous flow. Increase in Itr and Irf against time and temperature were attributed to an increase in crossing density at the junction surface. The activation energy of viscous flow, delta H, was measured and found to be around 8 kcal/mol and the back and forth activation energies (delta Erf and delta Etr) were measured and found to be around 49 and 53 kcal/mol for a reptating polymer chain across the junction surface. Diffusion of solvent molecules (chloroform) into the annealed latex coatings was followed by desorption of PMMA chains for the third set of films. Desorption of pyrene, P, labeled PMMA chains was monitored in real-time by the absorbance change of pyrene in the polymer-solvent mixture. A diffusion model with a moving boundary was employed to quantify real-time UVV data. Diffusion coefficients of desorbed PMMA chains were measured and found to be between 2 and 0.6 x 10-11 cm2 s-1 in the 100 and 275°C temperature range. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5771 [article]

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Comparison of methods to assess pigment dispersion / Sang T. Van in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 923 (12/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 923 (12/2001) . - p. 61-70 Titre : Comparison of methods to assess pigment dispersion Type de document : texte imprimé Auteurs : Sang T. Van, Auteur ; Bhaskar V. Velamakanni, Auteur ; Ronald R. Adkins, Auteur Année de publication : 2001 Article en page(s) : p. 61-70 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Distribution  dimension  particule  Propriété  rhéologique  Opacité  Contraste  Brillant  optique  Broyeur  rouleau  comparative  Méthode  mesure  Dispersion  Pigment  Broyage  Fabrication  Encre Index. décimale : 667.9 Revêtements et enduits Résumé : Two inks made with different red pigments were evaluated by common methods to assess the degree of pigment dispersion. One pigment is more difficult to disperse than the other in the vehicle used. The five methods that could detect changes in dispersion with each pass over a three-roll mill were a light scattering particle size distribution analyzer, a NPIRI fineness of grind gauge, gloss, contrast ratio measurements, and rheology. The gloss and contrast ratio measurements could detect changes with each pass over a three-roll mill only with a significant reduction in pigment particle size. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5772 [article]

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Characterization of absorptivities to solar radiation for colored pigments in coatings / Hong-You Guo in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 923 (12/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 923 (12/2001) . - p. 71-75 Titre : Characterization of absorptivities to solar radiation for colored pigments in coatings Type de document : texte imprimé Auteurs : Hong-You Guo, Auteur ; Ping Wang, Auteur ; Xiu-Yan Li, Auteur Année de publication : 2001 Article en page(s) : p. 71-75 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Etude  expérimentale'  Caractérisation  Réflectivité  Couleur  Blanc  Titane  Oxyde  'Pigment  organique'  minéral'  'Rayonnement  solaire'  'Absorption  optique'  'Propriété  Peinture  'Matériau  revêtement' Index. décimale : 667.9 Revêtements et enduits Résumé : Colored pigments absorptivities to solar radiation have been characterized quantitatively by measuring the absorption coefficients of the colored pigments mixed in white titanium dioxide standard coating. The standard coating contains white TiO2 with 17 % pigment volume concentration (PVC). Dry white coating with more than 134 µm thickness is opaque and used as a dispersion medium for colored pigments. The reflectances of the coatings of white TiO2 and three kinds of colored pigments (perylene black, toluidine red, and benzidine yellow) to solar radiation are measured by means of a UV-3100 recording spectrophotometer operating in the 250~2500 nm spectral range. It is found that the plots of lg 1/R (R, reflectance of coating to solar radiation) against Vcolored/VTiO2 (volume ratio of the colored pigment to TiO2 in coating) are straight lines of increasing slopes in the range of Vcolored/VTiO2 less than five percent. From the slopes of the straight lines, the absorption coefficients of colored pigments can be measured quantitatively. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5773 [article]

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Pigment dispersion : III / Zeno W. Wicks in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 923 (12/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 923 (12/2001) . - p. 77-83 Titre : Pigment dispersion : III Type de document : texte imprimé Auteurs : Zeno W. Wicks, Auteur ; S. Peter Pappas, Auteur ; Frank N. Jones, Auteur Année de publication : 2001 Article en page(s) : p. 77-83 Note générale : Bibliogr. Langues : Américain (ame) Tags : Méthode  mesure  Broyeur  rouleau  Appareil  agité  Broyage  humide  Sable  Corps  broyant  bille  boulet  disque  Equipement  Dispersion  Pigment  Fabrication  Peinture Index. décimale : 667.9 Revêtements et enduits Résumé : Pigments are manufactured with the particle size distribution that gives the best compromise of properties, but the particles often become cemented together into aggregates during processing. Breaking these aggregates and forming stable dispersions of optimally sized pigment particles is a critical process in the manufacture of coatings. Making dispersions involves three aspects: (1) wetting, (2) separation, and (3) stabilization. Most authors agree that there are three aspects to dispersion but different terms are used, sometimes with conflicting meanings. Be careful reading papers to know how an author is using the terms. Because of effects of the high surface tension and polarity of water, consideration of pigment dispersion is separated in three sections. The first section (JCT, October 2001, page 145), dispersion in organic media, usually solutions of resins in organic solvent, was discussed. Dispersion in aqueous media is treated in the Formulation of Mill Bases section in this issue. The third section covers the use of Dispersion Equipment and Processes as well as the Evaluation of the Degree of Dispersion. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5775 [article]

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