Drying regime maps for particulate coatings

Key microstructural properties of particulate coatings such as porosity and particle order are established during drying. Therefore, understanding the evolution of particulate distributions during drying is useful for designing coating properties. Here, a 1D model is proposed for the particle distri...

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Bibliographic Details
Published in:AIChE journal 2010-11, Vol.56 (11), p.2769-2780
Main Authors: Cardinal, Christine M, Jung, Yoon Dong, Ahn, Kyung Hyun, Francis, L.F
Format: Article
Language:English
Subjects:
Applied sciences
Brownian motion
Chemical engineering
Coatings
colloids
cryoSEM
Diffusion
Diffusion rate
Drying
Drying agents
Evaporation
Exact sciences and technology
Liquid-liquid and fluid-solid mechanical separations
Mathematical models
Microstructure
Peclet number
Porosity
Sedimentation
Sedimentation & deposition
setting/sedimentation
Settling
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Summary:Key microstructural properties of particulate coatings such as porosity and particle order are established during drying. Therefore, understanding the evolution of particulate distributions during drying is useful for designing coating properties. Here, a 1D model is proposed for the particle distribution through the coating thickness at different drying times and conditions, including Brownian diffusion, sedimentation, and evaporation. Effects of particle concentration on diffusion and sedimentation rates are included. Results are condensed onto a drying regime map which predicts the presence of particle surface accumulation or sediment based on two dimensionless numbers: the Peclet number and the sedimentation number. Cryogenic scanning electron microscopy (cryoSEM) is used to image the transient particulate distributions during the drying of a model system comprised of monodisperse silica particles in water. Particle size and evaporation rates are altered to access various domains of the drying map. There is good agreement between cryoSEM observations and model predictions. © 2010 American Institute of Chemical Engineers AIChE J, 2010
ISSN:0001-1541
1547-5905
DOI:10.1002/aic.12190