HWAHAK KONGHAK, Vol.32, No.1, 95-102, February, 1994
초임계유체내에서 고분자 용액의 상거동 및 분획
Phase Behaviors and Fractionation of Polymer Solutions in Supercritical Fluids
초록
Polystyrene-toluene-CO2 system에서 CO2의 농도를 변화시키면서 상거동을 관찰하여 LCST(lower critical solution temperature)와 UCST(upper critical solution temperature)를 실험적으로 결정하였으며, 액-액 상분리현상을 이용한 고분자용액의 분획실험을 하였다. 상거동 실험결과 CO2의 농도가 15.0wt%에서는 7.6-100℃의 실험온도 범위내에서 LCST만 관찰할 수 있었고, 16.2wt%에서는 LCST 뿐만 아니라 UCST도 관찰되었으며, 농도를 16.6wt% 로 증가시킬 때 LCST와UCST가 중첩되는 것을 관찰할 수 있었다. 초임계 CO2의 농도가 16.6wt%인 경우에 온도와 압력을 여러 가지로 변화시키면서 고분자용액의 분획시료를 얻었는데, 분자량과 유리전이온도(Tg)를 측정하여 다양한 분자량 분포를 갖는 분획된 시료의 해석을 시도하였다.
Through the observation of phase behaviors in polystyrene-toluene-CO2 systems by varying CO2 concentrations the LCST and UCST have been determined experimentally. Fractionation of those solutions has been performed utilizing liquid-liquid-liquid phase split phenomena. The experiment shows that only LCST has been detected when the concentration of CO2 is 15.0wt% for the temperature range from 7.6℃ to 100℃. We also observed UCST as well as LCST at 16.2wt% of CO2 and the dramatic merge of two critical solution temperature curves by increasing CO2 concentration to 16.6wt%. When the concentration of CO2 is 16.6wt%, the fractionated polymer samples have been obtained at different experimental conditions, and those samples have been analyzed in terms of molecular weights and glass transition temperatures.
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