关键词: 超临界流体脱挥, 质量传递, 扩散, PET聚酯, 乙二醇

Abstract: Most of residual volatiles in polymers, which normally result from synthesis processes of the polymers, have negative impacts on the end-use properties of the polymer materials. These volatiles should be minimized or at least be reduced to a level below the permissible limit. Conventional techniques for polymer devolatilization have shown limited effectiveness when the volatile concentration is at a low level. With the assistance of supercritical fluids, however, the operation for the removal of the volatiles from polymers can be enhanced. The quantities of the volatile, ethylene glycol (EG), in polyethylene terephthalate (PET) films at different times were determined in the presence of supercritical carbon dioxide (SC-CO₂) at a temperature of 343 K, pressure of 30 MPa and CO₂ flow rate of 4.0 L•min^-1, based on which the SC-CO₂-assisted removal of EG from PET film matrix was investigated. A mass transport model was derived by means of the mass transport theory.Comparison of the model predictions with experimental results showed that the model reflected the essential features of supercritical fluid devolatilization of polymers.

Key words: 超临界流体脱挥, 质量传递, 扩散, PET聚酯, 乙二醇