Drying of latex films and coatings: Reconsidering the fundamental mechanisms

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The two existing theories describing drying of latex films or coatings are reconsidered. Subsequently, a novel mathematical drying model is presented, the simulations of which can match and explain experimental drying rate data of two previous investigations with latex films. In contrast to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m), latex particle size (500-600 nm), initial polymer volume concentration (19-47 vol.%), and molecular weight of latex polymer (not quantified). Simulations also demonstrate that the transition from a constant to a falling drying rate in all cases takes place when the polymer volume concentration of the latex film is equal to that of hexagonal closest packed monodisperse spheres (74 vol.%). Consequently, the model has predictive properties and model inputs are only needed on the specific experimental (or field) conditions of interest. The effects on drying time of variations in relative humidity, wet film thickness, initial polymer volume concentration, and air flow velocity are simulated and analysed using the new model. (c) 2006 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalProgress in Organic Coatings
Volume57
Issue number3
Pages (from-to)236-250
ISSN0300-9440
DOIs
Publication statusPublished - 2006

Cite this

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title = "Drying of latex films and coatings: Reconsidering the fundamental mechanisms",
abstract = "The two existing theories describing drying of latex films or coatings are reconsidered. Subsequently, a novel mathematical drying model is presented, the simulations of which can match and explain experimental drying rate data of two previous investigations with latex films. In contrast to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m), latex particle size (500-600 nm), initial polymer volume concentration (19-47 vol.{\%}), and molecular weight of latex polymer (not quantified). Simulations also demonstrate that the transition from a constant to a falling drying rate in all cases takes place when the polymer volume concentration of the latex film is equal to that of hexagonal closest packed monodisperse spheres (74 vol.{\%}). Consequently, the model has predictive properties and model inputs are only needed on the specific experimental (or field) conditions of interest. The effects on drying time of variations in relative humidity, wet film thickness, initial polymer volume concentration, and air flow velocity are simulated and analysed using the new model. (c) 2006 Elsevier B.V. All rights reserved.",
author = "S{\o}ren Kiil",
year = "2006",
doi = "10.1016/j.porgcoat.2006.09.003",
language = "English",
volume = "57",
pages = "236--250",
journal = "Progress in Organic Coatings",
issn = "0300-9440",
publisher = "Elsevier",
number = "3",

}

Drying of latex films and coatings: Reconsidering the fundamental mechanisms. / Kiil, Søren.

In: Progress in Organic Coatings, Vol. 57, No. 3, 2006, p. 236-250.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Drying of latex films and coatings: Reconsidering the fundamental mechanisms

AU - Kiil, Søren

PY - 2006

Y1 - 2006

N2 - The two existing theories describing drying of latex films or coatings are reconsidered. Subsequently, a novel mathematical drying model is presented, the simulations of which can match and explain experimental drying rate data of two previous investigations with latex films. In contrast to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m), latex particle size (500-600 nm), initial polymer volume concentration (19-47 vol.%), and molecular weight of latex polymer (not quantified). Simulations also demonstrate that the transition from a constant to a falling drying rate in all cases takes place when the polymer volume concentration of the latex film is equal to that of hexagonal closest packed monodisperse spheres (74 vol.%). Consequently, the model has predictive properties and model inputs are only needed on the specific experimental (or field) conditions of interest. The effects on drying time of variations in relative humidity, wet film thickness, initial polymer volume concentration, and air flow velocity are simulated and analysed using the new model. (c) 2006 Elsevier B.V. All rights reserved.

AB - The two existing theories describing drying of latex films or coatings are reconsidered. Subsequently, a novel mathematical drying model is presented, the simulations of which can match and explain experimental drying rate data of two previous investigations with latex films. In contrast to previous model studies, but in agreement with observations, simulations suggest that during the falling rate period of the drying process of a latex film, a porous skin of partly coalesced latex particles is indeed formed, which limits transport of water vapour from the receding air-liquid interphase to the surface of the film. The value of the effective diffusion coefficient of water vapour in the dry and partly coalesced layer (7 x 10(-7) m(2)/s at 19-24 degrees C), the adjustable parameter of the model for the falling rate period, was found to be independent of initial wet film thickness (89-1322 mu m), latex particle size (500-600 nm), initial polymer volume concentration (19-47 vol.%), and molecular weight of latex polymer (not quantified). Simulations also demonstrate that the transition from a constant to a falling drying rate in all cases takes place when the polymer volume concentration of the latex film is equal to that of hexagonal closest packed monodisperse spheres (74 vol.%). Consequently, the model has predictive properties and model inputs are only needed on the specific experimental (or field) conditions of interest. The effects on drying time of variations in relative humidity, wet film thickness, initial polymer volume concentration, and air flow velocity are simulated and analysed using the new model. (c) 2006 Elsevier B.V. All rights reserved.

U2 - 10.1016/j.porgcoat.2006.09.003

DO - 10.1016/j.porgcoat.2006.09.003

M3 - Journal article

VL - 57

SP - 236

EP - 250

JO - Progress in Organic Coatings

JF - Progress in Organic Coatings

SN - 0300-9440

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ER -