Titre : |
Dielectric studies of epoxy/polyester powder coatings containing titanium dioxide, silica, and zinc oxide pigments |
Type de document : |
texte imprimé |
Auteurs : |
Emile C. Trottier, Auteur ; Stanley Affrossman, Auteur ; Richard A. Pethrick, Auteur |
Année de publication : |
2012 |
Article en page(s) : |
p. 525-539 |
Note générale : |
Bibliogr. |
Langues : |
Américain (ame) |
Catégories : |
Diélectriques Dioxyde de titane Epoxydes Oxyde de zinc Polyesters Revêtements poudre:Peinture poudre SiliceLa silice est la forme naturelle du dioxyde de silicium (SiO2) qui entre dans la composition de nombreux minéraux.
La silice existe à l'état libre sous différentes formes cristallines ou amorphes et à l'état combiné dans les silicates, les groupes SiO2 étant alors liés à d'autres atomes (Al : Aluminium, Fe : Fer, Mg : Magnésium, Ca : Calcium, Na : Sodium, K : Potassium...).
Les silicates sont les constituants principaux du manteau et de l'écorce terrestre. La silice libre est également très abondante dans la nature, sous forme de quartz, de calcédoine et de terre de diatomée. La silice représente 60,6 % de la masse de la croûte terrestre continentale.
|
Index. décimale : |
667.9 Revêtements et enduits |
Résumé : |
Dielectric measurements are reported covering a frequency range from 10?3 to 105 Hz and a temperature range from ~355 to 410 K for a pigmented epoxy/polyester resin powder coating system. A large low frequency ohmic conduction was observed in all these systems and the electrical modulus representation was used to aid analysis. A space charge relaxation indicative of heterogeneity in the matrix was observed in the pure resin and the pigmented coatings. In the pure resin, the heterogeneity is associated with nanoscale phase separation. A study with the resin modified with Modaflow, an ester copolymer dispersion agent, shows that the dipole relaxation is more ideal and the activation energy for dipole relaxation is reduced compared with that observed in the pure resin. The introduction of titanium dioxide pigment reduces the activation energy but also increases the magnitude of the ohmic conductivity and space charge contributions to the dielectric permittivity. All the systems exhibit heterogeneity and in the case of a pigmented system charge carriers can be introduced into the system by the pigment. Clear differences are observed between TiO2 produced via the chloride and sulfate routes, reflecting different levels of charge carriers and ion mobile in the resin system. High levels of mobile ions were also observed when zinc oxide and silica were used as pigments. |
Note de contenu : |
- EXPERIMENTAL : Materials : titanium dioxide pigments - Surface area - Other pigments - Resins - Formulation of powder coating - Dielectric measurements - Dielectric theory results and discussion
- RESULTS AND DISCUSSION : Unpigmented resin with modaflow - Unpigmented resin without modaflow
- RESIN CONTAINING TITANIUM DIOXIDE PIGMENT : Titanium dioxide produced via the chloride route : Titanium dioxide produced via the sulfate route - Investigation of the possible influence of zinc oxide and silica on the relaxations |
DOI : |
10.1007/s11998-012-9405-y |
En ligne : |
https://link.springer.com/content/pdf/10.1007%2Fs11998-012-9405-y.pdf |
Format de la ressource électronique : |
Pdf |
Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16024 |
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 9, N° 5 (09/2012) . - p. 525-539