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Thermodynamics of deformation of latex blend coatings and its implications for tailoring their properties / N. Agarwal in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 896 (09/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 896 (09/1999) . - p. 61-72 Titre : Thermodynamics of deformation of latex blend coatings and its implications for tailoring their properties Type de document : texte imprimé Auteurs : N. Agarwal, Auteur ; R. J. Farris, Auteur Année de publication : 1999 Article en page(s) : p. 61-72 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Calorimétrie Couches minces Déformations (mécanique) Essais dynamiques Latex Mélanges (chimie) Polyacryliques Revêtements -- Propriétés mécaniques:Peinture -- Propriétés mécaniques Revêtements en phase aqueuse:Peinture en phase aqueuse Thermodynamique Traction (mécanique) Index. décimale : 667.9 Revêtements et enduits Résumé : Acrylic-based latex blend coatings, comprising a hard (Tg=45°C) and soft (Tg= -5°C) phases are evaluated in terms of the total energy they absorb before failure in a tensile test. Simultaneous measurement of the work and heat of deformation using a novel technique of differential gas pressure stretch calorimetry enables an estimate of change in their internal energy by application of the first law of thermodynamics. As the hard phase content of the blend is increased from 0-100%, its stiffness and tenacity increase, while the toughness (i.e., the energy to failure) undergoes a maximum at an intermediate composition. A partitioning of the mechanical work into heat and internal energy over the complete range of blend composition highlights the result that a simultaneous maximization of the heat dissipation and energy absorption is necessary to maximize blend toughness. This provides a new framework in which the properties of blend systems can be tailored in terms of their stiffness and toughness to design improved coatings. Note de contenu : - BACKGROUND : A brief historical perspective - Theory of operation - Calorimeter schematic - Calibrations - EXPERIMENTAL : Materials and sample preparation - Techniques - RESULTS AND DISCUSSION : Thermo-mechanical characterization - Stretch-calorimetry Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17928 [article]

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Interfacial studies of crosslinked urethanes : part IV. Substrate effect on film formation in polyester waterborne polyurethanes / Marek W. Urban in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 896 (09/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 896 (09/1999) . - p. 73-78 Titre : Interfacial studies of crosslinked urethanes : part IV. Substrate effect on film formation in polyester waterborne polyurethanes Type de document : texte imprimé Auteurs : Marek W. Urban, Auteur ; Claudia L. Allison, Auteur Année de publication : 1999 Article en page(s) : p. 73-78 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Matériau  revêtement'  'Peinture  eau'  émulsion'  'Uréthanne  polymère'  'Formation  film'  Subjectile  'Propriété  surface'  'Tension  superficielle'  'Réaction  interface'  Réticulation  'Etude  expérimentale'  Métal  'Matière  plastique'  Verre Index. décimale : 667.9 Revêtements et enduits Résumé : These studies examine the effect of substrate surface tension on crosslinking reactions in waterborne polyurethanes (PUR) applied to tin-plated steel, steel, polypropylene (PP), thermoplastic olefin (TPO), and glass. The results show that, relative to tin-plated steel, removal of tin-plating from a steel substrate increases isocyanate (NCO) consumption by 42% near the film-substrate (F-S) interface. When PUR is allowed to crosslink on steel, PP, TPO, and glass, the NCO concentration is greater at the film-air (F-A) interface. Furthermore, crosslinking reactions result in a greater amount of urea-hydrogen bonded species near the F-S interface for all substrates. While an increase ofsubstrate surface tension decreases the amount of urea-hydrogen bonded carbonyl groups near the F-S interface, TPO was found to exhibit different behavior due to talc stratification near the surface. In this case, the presence of talc in WB-PUR coatings or thermoplastic substrates decreases the amount of hydrogen-bonded species and increases NCO consumption. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17941 [article]

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UV radiation curing of surface coatings based on ENR-cycloaliphatic diepoxide-glycidyl methacrylate system by cationic photoinitiators-optimization of process variables through response surface methodology / R. N. Kumar in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 896 (09/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 896 (09/1999) . - p. 79-88 Titre : UV radiation curing of surface coatings based on ENR-cycloaliphatic diepoxide-glycidyl methacrylate system by cationic photoinitiators-optimization of process variables through response surface methodology Type de document : texte imprimé Auteurs : R. N. Kumar, Auteur ; Woo Choon Kong, Auteur ; Abusamah Abubakar, Auteur Année de publication : 1999 Article en page(s) : p. 79-88 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Matériau  revêtement'  Peinture  Durcissement  'Rayonnement  UV'  'Caoutchouc  naturel  époxydé'  Diépoxyde  'Epoxyde  résine'  'Méthacrylate  de  glycidyle  copolymère'  Photoamorceur  'Propriété  mécanique'  Feuil  'Etude  expérimentale'  'Surface  réponse' Index. décimale : 667.9 Revêtements et enduits Résumé : This paper reports on the results of the ultraviolet curing of surface coatings based on cycloaliphatic diepoxide-epoxidized natural rubber (ENR)-glycidyl methacrylate (GMA) system with a cationic photoinitiator. The results reported in our earlier publication showed that ENR acts as a toughening agent for the otherwise brittle epoxy resin, and that GMA functions as a crosslinking agent in the system and promotes adhesion between the elastomeric domain and the resin matrix. In this paper, the results of the effect of operating variables on the properties of the cured film are reported. Response surface methodology (RSM) was employed to collect data and to establish the functional relationships between operating variables and performance characteristics of the cured coatings. The data are represented in three-dimensional response surface plots. These plots not only enable the interpretation of results, but also allow the determination of the optimum treatment combinations required to maximize the properties of the surface coatings. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17942 [article]

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Role of particle size on latex deformation during film formation / Charles S. Kan in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 896 (09/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 896 (09/1999) . - p. 89-97 Titre : Role of particle size on latex deformation during film formation Type de document : texte imprimé Auteurs : Charles S. Kan, Auteur Année de publication : 1999 Article en page(s) : p. 89-97 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Peinture  eau'  émulsion'  'Formation  film'  Déformation  'Dimension  particule'  'Température  transition  vitreuse'  'Etude  expérimentale' Index. décimale : 667.9 Revêtements et enduits Résumé : The ability of latex particles to deform and coalesce to form an integral film upon drying is an important property in many latex coating applications. Many theories have been proposed to account for the origin of the deformation forces. The capillary forces which depend inversely on particle size have been accepted as important for latex deformation and film formation. The minimum film forming temperature (MFFT) has been found to be a function of the particle size of latexes and has been used as evidence that the capillary forces are responsible for film formation. In this study, the deforming force at MFFT has been determined from the moduli of water-equilibrated latex polymers. No particle size dependence was observed. The magnitude of the deforming forces was at least an order of magnitude lower than that predicted by the capillary force theory. Electron microscopy of film formed below the MFFT, a condition that corresponds to early stage film formation, showed significant deformation, indicating that at the beginning of film formation, forces of magnitude predicted by the capillary force theory are present. However, the magnitude of the forces decreases rapidly as film formation progresses. The MFFT particle size dependency can be explained by the difference in the degree of water plasticization. Evidence that latexes of different particle size were plasticized by water to different extents was determined from the Tgs of the latex emulsions. Note de contenu : - EXPERIMENTAL : Materials - Preparation of unseeded latexes - Preparation of seeded latexes - Minimum film formation temperature - Dynamic mechanical spectroscopy - Glass transition temperature of latex emulsion - RESULTS AND DISCUSSION : Effect of particle size on MFFT - Estimation of deformation force in film formation process - Deformation forces in early stage of film formation - effect of latex particle size on the glass transition temperature of latex emulsions Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17943 [article]

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