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Scaling the long-term shear stability of aqueous pigment dispersions / Evagelos K. Athanassiou in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8944–8949 Titre : Scaling the long-term shear stability of aqueous pigment dispersions Type de document : texte imprimé Auteurs : Evagelos K. Athanassiou, Auteur ; Hanspeter Gradischnig, Auteur ; Peter Siemsen, Auteur Année de publication : 2009 Article en page(s) : pp. 8944–8949 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : ShearPigment  dispersions Résumé : The industrial application of paints today involves the handling of millions of tons of pigment dispersions. Shear and mechanical stress during pumping, storage, or processing significantly affect color and shelf life. Currently, mainly empirical test series and pilot-scale process models are used to assess the stability of such dispersions and provide marginal guidance when developing or testing large-scale paint applications. Scaling the stability against shear stress is particularly important for water-based metal pigment dispersions where damage to the pigment flakes causes their deterioration. The present work investigates the scaling of shear stress from the production line (>1000 tons/yr) to laboratory scale (100-g scale). We analytically show why the integrated shear stress on a specific dispersion can be deconvoluted into a series of individual shear stress contributions. These individual contributions can be accurately reproduced in the laboratory using a Couette-type shearing setup similar to a classical rheometer. As a representative example, a stable and a shear-sensitive paint from an automotive production line was sampled over 4 months of production. The evolving deterioration, color changes, and dispersion instability could be accurately reproduced using the scaling method outlined here. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017324 [article] Scaling the long-term shear stability of aqueous pigment dispersions [texte imprimé] / Evagelos K. Athanassiou, Auteur ; Hanspeter Gradischnig, Auteur ; Peter Siemsen, Auteur . - 2009 . - pp. 8944–8949. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8944–8949 Mots-clés : ShearPigment  dispersions Résumé : The industrial application of paints today involves the handling of millions of tons of pigment dispersions. Shear and mechanical stress during pumping, storage, or processing significantly affect color and shelf life. Currently, mainly empirical test series and pilot-scale process models are used to assess the stability of such dispersions and provide marginal guidance when developing or testing large-scale paint applications. Scaling the stability against shear stress is particularly important for water-based metal pigment dispersions where damage to the pigment flakes causes their deterioration. The present work investigates the scaling of shear stress from the production line (>1000 tons/yr) to laboratory scale (100-g scale). We analytically show why the integrated shear stress on a specific dispersion can be deconvoluted into a series of individual shear stress contributions. These individual contributions can be accurately reproduced in the laboratory using a Couette-type shearing setup similar to a classical rheometer. As a representative example, a stable and a shear-sensitive paint from an automotive production line was sampled over 4 months of production. The evolving deterioration, color changes, and dispersion instability could be accurately reproduced using the scaling method outlined here. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8017324