REMOVAL OF VOLATILE RESIDUES FROM POLYMERS BY SUPERCRITICAL CARBON-DIOXIDE

Experiments in removing volatile residues using supercritical carbon dioxide were carried out for three systems : benzene+poly (vinyl acetate), toluene+poly (vinyl acetate), and benzene +polystyrene, at 313K and 7.95MPa. The removal rate of benzene or toluene for the benzene or toluene + poly (vinyl acetate) systems was found to be faster than in the benzene+polystyrene system. This was explained by the difference of plasticity and dissolution rate of carbon dioxide between poly (vinyl acetate) and polystyrene. In the benzene+polystyrene system, the removal ratio by extraction was increased with increase in the initial concentration of benzene. It was considered that plasticization with increase in initial benzene concentrations affected the removal ratio by extraction. Also, it was shown that the removal ratio by decompression was increased with increase in the quantity of carbon dioxide dissolved in the polymer. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.