Advances in emulsion polymerization for coatings applications / Mohamed S. El-Aasser in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 920 (09/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 920 (09/2001) . - p. 51-63 Titre : Advances in emulsion polymerization for coatings applications : Latex blends and reactive surfactants Type de document : texte imprimé Auteurs : Mohamed S. El-Aasser, Auteur ; E.-D. Sudol, Auteur ; Victoria L. Dimonie, Auteur ; Eric S. Daniels, Auteur ; Xiaoru Wang, Auteur ; Jiansheng Tang, Auteur Année de publication : 2001 Article en page(s) : p. 51-63 Note générale : Bibliogr. Langues : Américain (ame) Tags : Matériau  revêtement  Peinture  eau  émulsion  Liant  Préparation  Polymérisation  Latex  Mélange  Adjuvant  Agent  surface  Distribution  dimension  particule  Propriété  optique  Feuil  Brillant  Styrène  polymère  Groupe  carboxyle  Etude  expérimentale Index. décimale : 667.9 Revêtements et enduits Résumé : The utilization of latex blends to prepare zero-VOC coatings and the use of reactive surfactants in emulsion polymerization are two advances in waterborne technology that are of increasing interest to coatings formulators. The first part of this paper focuses on an investigation of the influence of the interface between high and two Tg latex particles on the glass and surface morphologies of films obtained from model latex blends. Glass was influenced by the concentration of carboxyl groups present on the surface of the latex particles (optimal concentration for maximum gloss 3% on the high Tg particles), the degree of neutralization of these groups (higher glass with increased extent of neutralization), the type and concentration of the neutralizing base (higher gloss for stronger bases), and the presence of added surfactant (higher gloss with added surfactant). Gloss was found to be correlated with the surface smoothness of the film. The kinetics, particle size, molecular weight, and location of the reactive surfactant after polymerization, as well as the contact angle of films prepared from these latices, are examined in the second part of this paper. The polymerization rate profiles were similar to those obtained using a conventional surfactant ; however, the dependency of the rate on the number of particles was significantly lower. The amount bound increased and the molecular weight decreased with increasing surfactant concentration. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5746 [article]

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Process model for latex film formation / Alexander F. Routh in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 73, N° 916 (05/2001)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 73, N° 916 (05/2001) . - p. 41-48 Titre : Process model for latex film formation : Optical clarity fronts Type de document : texte imprimé Auteurs : Alexander F. Routh, Auteur ; William B. Russel, Auteur ; Jiansheng Tang, Auteur ; Mohamed S. El-Aasser, Auteur Année de publication : 2001 Article en page(s) : p. 41-48 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Formation de film Modèles mathématiques Revêtements en phase aqueuse -- Séchage:Peinture en phase aqueuse -- Séchage Index. décimale : 667.9 Revêtements et enduits Résumé : We examined the drying behavior of latex both theoretically and experimentally. The theory extends a model for horizontal drying fronts in films with nondeformable particles to incorporate particle deformation by a capillary deformation mechanism. The pressure in the fluid, causing particle compaction, arises from flow through the packed bed to ensure evaporation from all wet areas of the film. We predicted the position of a front of volume fraction unity passing across a semi-infinite film as it dries. Experimentally, the position of the transition from a cloudy film to optical clarity was tracked visually in films comprised of either single component soft latex particles, 20[degrees]C above the glass transition, or a blend containing 35% non-deformable hard latex particles. For an initial volume fraction of 0.33, we found excellent agreement between theory and experiment. For an initial volume fraction of 0.05, the agreement is less, although still qualitative. The limitations of the model with respect to t he knowledge of physical parameters and initial conditions are discussed. One major implication of the model is that deformation of soft latex particles displaces large amounts of water and, consequently, slozvs progression of the drying front. Harder particles and shallow initial film profiles produce more pronounced drying fronts. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5728 [article]

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