| 摘要 |
PURPOSE:To crystallize an amorphous polymer easily at a temperature lower than its Tg, to impart thereto a microvoid structure useful for a separation membrane or the like and to increase its gas adsorptivity, etc., by contacting it with pressurized carbon dioxide gas. CONSTITUTION:An amorphous polymer (e.g., amorphous polyethylene terephthalate or amorphous polycarbonate) is placed in a pressure vessel and is crystallized by contact with pressurized carbon dioxide gas to obtain the purpose crystallized amorphous polymer. It is suitable that the pressure of the carbon dioxide is about 10-100atm and the temperature in the crystallization treatment is near the Tg of the polymer. By performing the crystallization in such a way that one surface of an amorphous polymer film is exposed to air and the other is exposed to pressurized carbon dioxide gas, it is possible to produce a concentration gradient of sorbed carbon dioxide gas within the film. Therefore, a crystallized polymer film having a density gradient along the thickness of the film and suited as a separation membrane can be obtained.
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