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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Film formation from conventional and miniemulsion latex systems containing dimethyl meta-isopropenyl benzyl isocyanate (TMI) - a functional monomer/crosslinking agent / Yoshimi Inaba in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 66, N° 833 (06/1994)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 66, N° 833 (06/1994) . - p. 63-74 Titre : Film formation from conventional and miniemulsion latex systems containing dimethyl meta-isopropenyl benzyl isocyanate (TMI) - a functional monomer/crosslinking agent Type de document : texte imprimé Auteurs : Yoshimi Inaba, Auteur ; Eric S. Daniels, Auteur ; Mohamed S. El-Aasser, Auteur Année de publication : 1994 Article en page(s) : p. 63-74 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Copolymère styrène acrylate de butyle Formation de film Isocyanates Polymérisation en émulsion Réticulants Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : A series of model styrene (St)/n-butyl acrylate (BA) copolymer latexes with glass transition temperatures below room temperature were prepared by either conventional or miniemulsion polymerization techniques as model systems for studies of film formation. The functional monomer TMI® (META) (dimethyl meta-isopropenyl benzyl isocyanate) was used as a functional monomer/crosslinking agent. A small amount of methacrylic acid (MAA) was introduced in some formulations to enhance the crosslinking reactions. A redox initiation system was used to reduce premature crosslinking during the polymerization. A combination of an ionic surfactant (sodium lauryl sulfate) and co-surfactant (hexadecane or cetyl alcohol) was used as the mixed emulsifier for the miniemulsion system. This paper describes the performance of TMI as a crosslinking agent and the effects of the combination of TMI and MAA on the latex film formation process. Note de contenu : - EXPERIMENTAL : Materials - Miniemulsification - Polymerization - Evaluation methods - RESULTS AND DISCUSSION : Effect of the crosslinking agent concentration - Effect of initiator concentration - Effect of BA/St ratio - Influence of emulsifier concentration and differences between mixed emulsifier systems - Differences between latex film dried from St/BA/TMI/MAA copolymer latex and a blend of St/BA/TMI with St/BA/MAA copolymer latexes with varying TMI/MMA ratios Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18643 [article]

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Miniemulsions : Overview of research and applications / Mohamed S. El-Aasser in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 1, N° 1 (01/2004)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 1, N° 1 (01/2004) . - p. 21-31 Titre : Miniemulsions : Overview of research and applications Type de document : texte imprimé Auteurs : Mohamed S. El-Aasser, Auteur ; E.-D. Sudol, Auteur Année de publication : 2004 Article en page(s) : p. 21-31 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cinétique chimique Latex Miniémulsions Nucléation Polymères en émulsion Polymérisation Polymérisation en émulsion Index. décimale : 667.9 Revêtements et enduits Résumé : Since their discovery 30 years ago, miniemulsions have been the subject of numerous investigations ranging from the fundamental to the applied. This unique type of oil-in-water emulsion is chiefly characterized by its droplet size and relative stability. High shear is typically applied today to create the small size droplets (anywhere in the range of 50-500 nm) and the combination of a surfactant and a low molecular weight, highly water insoluble costabilizer is used to maintain their stability against collisional and diffusional (Ostwald ripening) degradation. The low molecular weight of the costabilizer is also responsible for the high swelling capacity of the droplets and polymer particles (made by emulsification of polymer solutions, polymerization of monomer miniemulsions, or a combination of these). These features of high stability and swelling capacity distinguish miniemulsions from conventional emulsions and have been exploited to make latexes not possible by conventional emulsification or emulsion polymerization processes. These include artificial latexes made by direct emulsification of a polymer solution followed by removal of the solvent, synthetic latexes made by polymerization of monomer miniemulsions, hybrid latexes made by emulsification of a monomer/polymer solution followed by polymerization, and encapsulated latexes. Most recently miniemulsions have been applied in controlled radical polymerizations whereby relatively narrow molecular weight polymers are produced. In general, our research efforts in miniemulsions have covered the fundamentals of their formation and stabilization, polymerization kinetics, and mechanisms, and look forward to possible applications. An overview of this research is presented here. DOI : 10.1007/s11998-004-0021-3 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-004-0021-3.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3929 [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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