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 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 864 (01/1997) . - p. 97-107