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Studies of latex paint films exposed to aqueous SO 2 : pH effects
Author(s) -
Xu J. R.,
Balik C. M.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070390911
Subject(s) - aqueous solution , distilled water , chemistry , diffusion , leaching (pedology) , inorganic chemistry , nuclear chemistry , chromatography , organic chemistry , soil water , physics , environmental science , soil science , thermodynamics
Latex paint films containing the acid‐soluble extender calcium carbonate have been exposed to aqueous SO 2 and other acidic solutions to evaluate the effects of acidic deposition at different pH values on the coatings. CaCO 3 is completely removed from these films upon immersion in acidic solutions. The leaching process was monitored with weight loss and infrared measurements. The removal rate was found to be strongly dependent on pH, decreasing with increasing pH. Removal of CaCO 3 occurs even for distilled water which has been allowed to equilibrate with atmospheric CO 2 (pH 5.6). The removal rate seems to depend only on [H + ]; the identity of the acidic anion is apparently insignificant. An empirical relation between the rate of removal and pH was formulated from the weight loss data. The analyses of the results from both weight loss and infrared methods suggested that the mechanism of removal at pH 2.0 is diffusion controlled, whereas a chemical reaction involving H + becomes more important at higher pH values.