Absorption behavior of vinyl chloride/calcium carbonate and pressure/temperature/conversion relationship for vinyl chloride suspension polymerization in the presence of calcium carbonate

Abstract

The absorption of vinyl chloride (VC) on surface-treated light-grade and nano-scale calcium carbonate (CaCO 3), and VC suspension polymerization in the presence of CaCO 3 were carried out in a 5 L autoclave. It showed that the absorption of VC on CaCO 3 increased with the partial pressure of VC up to a critical point. Nano-scale CaCO 3 was more effective in absorbing VC than light-grade CaCO 3 at the same temperature and partial pressure of VC due to its greater surface area. The absorption behavior of VC/CaCO 3 follows Langmuir isothermal equation. In view of the absorption of VC on CaCO 3, Xie’s model [J. Appl. Polym. Sci. 34 (1987) 1749] was modified to relate pressure, temperature, the amount of CaCO 3 and conversion for VC suspension polymerization in the presence of CaCO 3. The model simulation showed that VC conversions at the pressure drop point and at a certain pressure drop decreased with the increase of the amount of added CaCO 3, and the influence of nano-scale CaCO 3 was greater than that of light-grade CaCO 3. The simulated VC conversions fitted well with that obtained from VC suspension polymerizations in the presence of different amounts of light-grade or nano-scale CaCO 3.