Stress development during drying of calcium carbonate suspensions containing carboxymethylcellulose and latex particles
Date
2004
Authors
Wedin, Par
Martinez, Carlos J
Lewis , Jennifer A
Daicic , John
Bergstrom , Lennart
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Publisher
Academic Press
Abstract
Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying stress, weight loss, and relative humidity. Specifically, the influence of two organic binders on drying stress evolution was investigated: (1) carboxymethylcellulose, a water-soluble viscosifying aid, and (2) a styrene-butadiene latex emulsion of varying glass transition temperature. The stress histories exhibited three distinct regions. First, a period of stress rise was observed, which reflected the capillary tension exerted by the liquid on the particle network. Second, a maximum stress was observed. Third, it was followed by a period of either stress decay or rise depending on the organic species present. Significant differences in stress histories were observed between coatings containing soluble and nonsoluble binders. Maximum drying stresses (σmax) of 0.2-0.5 MPa were observed for coatings produced from pure calcium carbonate or calcium carbonate-latex suspensions, whereas coatings with carboxymethylcellulose exhibited substantially higher σmax values of 1-2 MPa. Upon drying, these coatings were quite hygroscopic, such that cyclic variations in relative humidity induced large cyclic changes in residual stress.
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Keywords
Keywords: Atmospheric humidity; Binders; Coatings; Glass transition; Latexes; Residual stresses; Drying stress; Stress decay; Calcium compounds; calcium carbonate; carboxymethylcellulose; latex; aqueous solution; article; dispersion; emulsion; glass transition temp Calcium carbonate; Carboxy methylcellulose; CMC; Drying; Latex; Paper coating; PCC; Stress evolution
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Source
Journal of Colloid and Interface Science
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Journal article
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2037-12-31
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