[article]
| Titre : |
Interdiffusion and crosslinking in thermoset latex films |
| Type de document : |
texte imprimé |
| Auteurs : |
Mitchell A. Winnik, Auteur |
| Année de publication : |
2002 |
| Article en page(s) : |
p. 49-63 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Tags : |
Article synthèse Carbodiimide polymère Mélamine résine Acrylamide dérivé Diffusion mutuelle Réticulation Formation film Thermodurcissable Peinture émulsion eau Matériau revêtement |
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Thermoset latex systems represent an attractive approach to obtaining the high performance needed in many different kinds of industrial coatings, while at the same time satisfying the growing requirement for environmental friendliness. In these coatings, in the dispersed state, the reactive groups are packaged inside of polymer particles. These latex particles deform as the coating dries to form a transparent binder phase. The useful properties of mechanical strength, as well as scrub and solvent resistance, develop over time. This paper focuses on the idea that to achieve the desired properties in a thermoset latex coating, one has to pay proper attention to the relative rates of polymer diffusion and cross-linking in the coating. Strength in these films develops as a consequence of chains that connect crosslink points on opposite sides of interface formed between a jacent particles in the film. Thus polymer diffusion must precede extensive bond formation created by the crosslinking chemistry. This paper reviews fundamental concepts and then describes experiments in three separate systems, in which my students have studied both the rates of polymer diffusion and the rates of the crosslinking reaction. These experiments show that the formulator has a number of tools that can be used to vary the relative rates of these processes. Catalyst strength and concentration will affect the reaction rote. Polymer chain length will have a large influence on the polymer diffusion rate. Temperature changes will often have a larger effect on the polymer diffusion rate than on the rate of the crosslinking reaction, because the effective activation energy for diffusion (through changes in free volume) are normally larger than the activation energy for the chemical reaction. |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5674 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 925 (02/2002) . - p. 49-63
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Interdiffusion and crosslinking in thermoset latex films in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 925 (02/2002)
