Separating Polymer Solutions with Supercritical Fluids. 2. Polystyrene-Toluene-Ethane

摘要

The effect of supercritical ethane on the high-pressure phase behavior of the polystyrene-toulene system is experimentally investigated. Adding 17.8 wt-% ethane to the polystrene-toulene solution lowers the temperature of the lower critical solution temperature (LCST) curve by 162 C, 22.5 wt-% lowers the temperature of the LCST curve by 231 C, and with 24.9 wt-% the LCST curve is shifted to such low temperatures that it merges with the upper critical solution temperature (UCST) curve. In practice this means that polymer solutions can be separated at lower temperatures where thermal degradation of the polymer is less. Also, greater than 99 wt-% of the polystyrene is recovered in the polymer-rich phase after the solution phase splits. Preliminary results are reported on the effects of shearing (i.e. mixing) and polymer entanglement/disentanglement times on the location of LCST and UCST curves in pressure-temperature (P-T) space. Patterson's correstates treatment is used to model the LCST data.