AbstractLatex paint films containing the acid‐soluble extender calcium carbonate have been exposed to aqueous SO2and other acidic solutions to evaluate the effects of acidic deposition at different pH values on the coatings. CaCO3is 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 CaCO3occurs even for distilled water which has been allowed to equilibrate with atmospheric CO2(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 value
展开▼
