Dry coating of talc particles with fumed silica: Influence of the silica concentration on the wettability and dispersibility of the composite particles

Even though dispersion operations have been the object of several investigations, the importance of the various parameters and especially the physicochemical and surface properties are rarely treated. Dry particle coating can be used to create new-generation materials by combining different powders...

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Bibliographic Details
Published in:Powder technology 2011-03, Vol.208 (2), p.372-377
Main Authors: Lefebvre, G., Galet, L., Chamayou, A.
Format: Article
Language:English
Subjects:
Applied sciences
aqueous solutions
Chemical engineering
Coating
coatings
dispersibility
Dispersion
Dispersions
Dry coating
Drying
Engineering Sciences
Exact sciences and technology
hydrophobicity
Miscellaneous
Particulate composites
powders
Shear
Silica
Silicon dioxide
Solid-solid systems
solvents
Talc
Talcs
Wettability
Work of adhesion
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Summary:Even though dispersion operations have been the object of several investigations, the importance of the various parameters and especially the physicochemical and surface properties are rarely treated. Dry particle coating can be used to create new-generation materials by combining different powders exhibiting different physical and/or chemical properties. In such processes relatively large particles (host particles) are mechanically coated with fine particles (guest particles), without using solvents and subsequent drying, to create new functionalities or to improve initial characteristics. The purpose of this study is to modify the surface of Talc particles by dry coating with different concentrations of hydrophobic Silica (Aerosil R972®), to examine the effect of the coating on the wettability of the coated Talc particles and to study the effects on the dispersibility of these same composite particles. Dry coating is found to modify the surface of Talc particles and to control their wettability and dispersibility in aqueous solutions. Dry coating with a Cyclomix high shear mixer is used to modify the surface of host Talc particles with different concentrations of guest Silica particles. The effect on the work of adhesion of the composite particles with respect to water is measured by the sessile drop method and these measurements are used to study the kinetics of dispersion of the particles in water. [Display omitted]
ISSN:0032-5910
1873-328X
DOI:10.1016/j.powtec.2010.08.031