Dynamic Supercritical Fluid Devolatilization of Polymers

A number of studies have been reported on the applications of supercritical fluids to polymeric processes. The presence of volatiles can affect the end-use properties of polymer materials. Therefore, these volatiles must be reduced to a level below the maximum permissible limit. Conventional heat-relevant techniques for polymer devolatilization sometimes have limited effectiveness. Devolatilization with supercritical fluids, however, can enhance removal of volatiies from polymers. A model for diffusion-limited extraction is used to characterize dynamic supercritical fluid devolatilization of spherical polymer particles. The rate of supercritical fluid devolailization for styrene/polystyrene system is measured at 343 K and 18 MPa and at CO2 flow rate of 1.93, 3.27 and 5.62L·min-1, respectively. The model analysis, which is consistent with experimental results, indicates that the supercritical fluid devolatilization is not solubility-limited but diffusion-limited when CO2 flow rate is above 4.00L·min-1更多还原