Characterization of particle coalescence in waterborne coatings using atomic force microscopy / R. M. Rynders in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 67, N° 845 (06/1995)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 67, N° 845 (06/1995) . - p. 59-69 Titre : Characterization of particle coalescence in waterborne coatings using atomic force microscopy Type de document : texte imprimé Auteurs : R. M. Rynders, Auteur ; Charles R. Hegedus, Auteur ; Andrew G. Gilicinski, Auteur Année de publication : 1995 Article en page(s) : p. 59-69 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Coalescence (Sciences physiques) Microscopie à force atomique Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Atomic force microscopy (AFM) was used to image coatings formed from blends containing various ratios of three waterborne acrylic/polyurethane hybrid polymers. Tapping and contact mode AFM were evaluated for this application, and tapping mode proved to be the best method due to the low friction forces. It was shown that when the tip and feature sizes were similar, the superposition of the tip morphology on the surface features in the AFM image was significant. AFM imaging of gold colloids dispersed on mica and scanning electron microscopy of the tip were used to characterize the AFM tips. A method was developed to estimate the tip radii; in turn, the tip size was accounted for in analyzing the dimensions of the coating surface features. The degree of particle coalescence was evaluated from the AFM images. The polymer blends were ranked according to the degree of particle coalescence; and the results correlated well with other methods of characterization. Note de contenu : - INTRODUCTION : Coating performance issues - AFM imaging issues - EXPERIMANTAL : Coating sample preparation - Atomic force microscopy - Scanning electron microscopy - Electrochemical impedance spectroscopy - Prohesion cabinet exposures - RESULTS AND DISCUSSION : Part I : evaluation of imaging methods - Part II: evaluation of polymer film formation Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18517 [article]

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Film formation mechanism of two-component waterborne polyurethane coatings / Charles R. Hegedus in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 68, N° 852 (01/1996)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 68, N° 852 (01/1996) . - p. 51-61 Titre : Film formation mechanism of two-component waterborne polyurethane coatings Type de document : texte imprimé Auteurs : Charles R. Hegedus, Auteur ; Andrew G. Gilicinski, Auteur ; Robert J. Haney, Auteur Année de publication : 1996 Article en page(s) : p. 51-61 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Coalescence (Sciences physiques) Dispersions et suspensions Formation de film Isocyanates Polyuréthanes Réactions chimiques Revêtements bi-composant:Peinture bi-composant Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Two-component (2K) waterborne polyurethane coatings are a new technology which has been demonstrated in a number of heavy duty applications. They exhibit performance properties equivalent to 2K solvent-borne polyurethanes, with the advantage of reduced volatile organic compounds (VOCs). Although the use of these systems has been demonstrated successfully, the details of their film formation mechanism have not been established. The objective of this work was to propose and confirm the film formation mechanism of these systems. A dynamic series of interrelated events which occur during the process was identified using a number of analytical techniques to study two isocyanate/ hydroxyl functional dispersion systems. The mechanism is presented in terms of an event timeline that chronicles the critical events which occur prior to and after application of the coating. Film property development after application also was evaluated and these results were analyzed in terms of the proposed film formation mechanism. Note de contenu : - BACKGROUND ON FILM FORMATION - PROPOSED FILM FORMATION MECHANISM FOR 2K WATERBORNE POLYURETHANE COATINGS - EXPERIMENTAL : Materials and coating preparation - Equipment and procedures - RESULTS AND DISCUSSION : Particle coalescence in the admixed state - Isocyanate reaction in the admixed state - Evaporation of volatiles and particle coalescence after application - Isocyanate reaction afetr application - Development of film integrity Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18310 [article]

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