Dépouillements

Predicting in-service weatherability of automotive coatings : A new approach / David R. Bauer in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 864 (01/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 864 (01/1997) . - p. 85-96 Titre : Predicting in-service weatherability of automotive coatings : A new approach Type de document : texte imprimé Auteurs : David R. Bauer, Auteur Année de publication : 1997 Article en page(s) : p. 85-96 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Automobiles -- Revêtements:Automobiles -- Peinture Délaminage Durée de vie (Ingénierie) Photodétérioration Résistance aux conditions climatiques Index. décimale : 667.9 Revêtements et enduits Résumé : The prediction of long-term weatherability of coatings has always been a difficult task. This task has been made significantly more difficult by the recent, rapid changes in coatings technology. Conventional weathering protocols which rely on observation of appearance changes after outdoor or laboratory exposures have not always been successful in anticipating in-service failures. This paper discusses the reason for this and describes a new approach for estimating in-service weatherability in coatings. The formalism begins by identifying specific failure modes and developing time-to-failure models which are based on fundamental studies of the chemistry and physics of failure. The statistical variation of the key material, process, and exposure parameters in the failure model are described in terms of distribution functions. Since photooxidation plays a critical role in most weathering issues, a specific distribution function for exposure harshness is estimated that can be used to describe the variation in photooxidation rate under actual in-service conditions. By combining a specific failure model with in-service variations in the key parameters, it is possible to estimate in-service failure rates as a function of material and processing variables, thus, allowing for improved risk assessment of any proposed material or processing change. The formalism also provides clearer direction in the design and use of specific laboratory and outdoor exposures in predicting performance. The method is illustrated by deriving distributions of time-to-failure based on two different hypothetical mechanisms of photo-induced coating delamination. Note de contenu : - ESTIMATION OF AN EXPOSURE DISTRIBUTION FUNCTION - DEVELOPMENT OF MODELS OF TIME-TO-FAILURE : Constant UV light transmission - Determination resulting from loss of UVA Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18077 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
003533	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Mechanistic considerations of particle size effects on film properties of hard/soft latex blends / Sarah T. Eckersley in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 864 (01/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 864 (01/1997) . - p. 97-107 Titre : Mechanistic considerations of particle size effects on film properties of hard/soft latex blends Type de document : texte imprimé Auteurs : Sarah T. Eckersley, Auteur ; Bradley J. Helmer, Auteur Année de publication : 1997 Article en page(s) : p. 97-107 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Couches minces Latex Microscopie électronique à balayage Revêtements -- Propriétés mécaniques:Peinture -- Propriétés mécaniques Revêtements en phase aqueuse:Peinture en phase aqueuse Taille des particules Index. décimale : 667.9 Revêtements et enduits Résumé : Blends of hard (Tg ∼ 60 °C) and soft (Tg ∼ 0°C) latexes were studied as a function of particle size ratio (Rsoft/Rhard) and blend ratio (mass soft phase/ mass hard phase). Addition of hard phase latex to the soft film forming latex significantly improved block resistance, even at blend ratios as low as 70/30. Film properties were not sacrificed, except at high concentrations of the hard phase (50/50). For a given blend ratio, the particle size ratio had a dramatic effect on the block resistance. For a 70/30 blend ratio, the block resistance of a blend with Rsoft/Rhard = 4.0 was equivalent to that of a control latex having the same overall composition, but with a minimum film temperature 20°C higher than the blend. The phenomenon can be explained in terms of the bulk and surface contributions to adhesion. The hard phase increases the elastic modulus (G') of the film. The magnitude of G' was found to increase with increasing Rsoft/Rhard, an effect that is consistent with percolation theory. The effect of particle size ratio on the surface contribution to adhesion can be explained by particle packing. Visual models indicate that a high apparent surface concentration of hard particles would be expected for a large value of Rsoft/Rhard, given ideal packing conditions. This effect was confirmed by scanning electron microscopy. Note de contenu : - EXPERIMENTAL : Emulsion polymerization - Minimum film temperature - Dynamic mechanical spectroscopy - Tensile testing - Differential scanning calorimetry - Particle size determination - Scanning electron microscopy - Block testing - RESULTS AND DISCUSSION : Blend ratio and high particle size ratio - Low particle size ratio - Mechanistic considerations - Bulk film characteristics - Percolation theory - Particle packing Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18078 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
003533	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Rheology of waterborne coatings / R. D. Hester in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 864 (01/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 864 (01/1997) . - p. 109-114 Titre : Rheology of waterborne coatings Type de document : texte imprimé Auteurs : R. D. Hester, Auteur ; D. R. Squire, Auteur Année de publication : 1997 Article en page(s) : p. 109-114 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Epaississants Revêtements en phase aqueuse -- Additifs:Peinture en phase aqueuse -- Additifs Rhéologie Index. décimale : 667.9 Revêtements et enduits Résumé : The rheology of a latex paint must be controlled to produce an acceptable coating. Conditions vary as a paint is sequentially taken from storage, applied to a substrate and then cured in place. As shown byTable 1, desirable films are produced only when paint viscosities and yield points are controlled at each process step. Thus, an understanding and control of paint rheology are essential if high quality coatings are to be produced from latex paints. Note de contenu : - ASSOCIATIVE THICKENERS : Hydrophobe formation thermodynamics - Advantages of associative thickeners - disadvantages of associative thickeners - Rheology of associative thickeners - Dynamic mechanical analysis of latex coatings - Proposed thickening mechanisms in latex systems - Chain entanglement - Particle bridging - Micellar bridging - Rheology during latex coating curing - Rheology during leveling Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18093 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
003533	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Waterborne coatings / Rich Johnson in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 864 (01/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 864 (01/1997) . - p. 117-121 Titre : Waterborne coatings : An overview of waterborne coatings : a formulator's perspective Type de document : texte imprimé Auteurs : Rich Johnson, Auteur Année de publication : 1997 Article en page(s) : p. 117-121 Langues : Américain (ame) Catégories : Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Waterbornes have been experiencing technological growth for the past 20 years, but it is not a steady growth. In the last five years we have seen an unprecedented increase in new technologies available to the formulator - technologies such as improved dispersions, high performance latexes, new formulation techniques, and unique additives. These changes are the result of regulatory and environmental concerns which make it necessary for formulators to constantly keep up to date with the technology just to compete. Staying informed is worth the effort because, with current information, you can develop waterbornes with equal or better properties than conventional systems. The challenge : finding, using and personalizing the new technologies, to come up with a truly superior low VOC coating. As we have all experienced, meeting the challenge can be difficult. Almost every coatings magazine you pick up tells you about these successful low VOC waterbornes by using comparison charts and testing results ; but they invite you to the party but forget to give you the directions. Most of the high performance low VOC coatings referred to in these articles are blends of latex and water-reducible or dispersion and water-reducible systems. So what you need to know is how to formulate so you can yield the best of both worlds. This article will overview waterbornes from a practical formulating point of view and attempt to shed some light on how to achieve specific properties in water systems. First we will deal with the odd dilemma of differentiating between the types of waterbornes, then we will look into resin choices, facets of formulation, and finally, where to expect new technologies. Note de contenu : - IS A LATEX A DISPERSION ; IS IT AN EMULSION ? - WHAT IS THE DIFFICULTY IN FORMULATING WATERBORNE PAINTS ? : Waterborne resins-advantages and disadvantages - Manufacturing - Baking systems - Application equipment - General formulation points - WHERE SHOULD YOU LOOK FOR THE NEXT BREAKTHROUGH ? - OTHER CONSIDERATIONS Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18290 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
003533	-	Périodique	Bibliothèque principale	Documentaires	Disponible