The sorption properties of supercritical carbon dioxide in poly (ethylene glycol) and poly (ethylene oxide) with high-pressure thermogravimetry-differential thermal analysis

In the investigation of polymer-supercritical fluid systems, it is particularly important to study the sorption and plasticization effect of supercritical fluids. In this work, the sorption and plasticization effect of supercritical carbon dioxide in poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO) were directly measured with a new in situ high-pressure thermogravimetry-differential thermal analysis (TGDTA) based on magnetic suspension. The sorption of carbon dioxide in molten PEG and PEO increased almost linearly with pressure. Henry's constant values, K-p, were evaluated using the experimental data. A linear expression between ln(1/K-p) and (Tc/T)(2) was shown for PEG/CO2 and PEO/CO2, systems. Compressed carbon dioxide gas depressed the melting points of PEG and PEO. The melting point of PEG and PEO decreases linearly with pressure of carbon dioxide, giving a dT(m)/d(p) value of -2.04 degreesC/MPa and - 1.24 degreesC/mPa, respectively.