Abstract
In this work, the glass transitions of poly(methyl methacrylate) and polystyrene in compressed gaseous acetone/carbon dioxide were measured by an in situ creep compliance method at pressures lower than 7.0 MPa and at 318−338 K. When a small amount of acetone (x = 0.01−0.02) was added to a polymer-compressed carbon dioxide system, the glass transition pressure of polymer was further depressed by 1.0−4.0 MPa. The observed glass transition pressure depression increased with the acetone concentration in carbon dioxide and decreased with the temperature rise. A simple model was used to estimate the glass transition temperature depressions for the polymers in compressed gaseous acetone/carbon dioxide solution. The calculated results were in good agreement with the determined ones, except for the retrograde vitrification region.
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