Crystallization of bisphenol a polycarbonate induced by supercritical carbon dioxide
01 Jul 1987-Journal of Polymer Science Part B (John Wiley & Sons, Inc.)-Vol. 25, Iss: 7, pp 1511-1517
TL;DR: In this paper, supercritical carbon dioxide readily induces crystallization in bisphenol A polycarbonate and the degree of crystallinity increases sharply as the CO2 pressure is raised from 100 to 300 atm but levels off thereafter.
Abstract: Supercritical carbon dioxide readily induces crystallization in bisphenol A polycarbonate. Crystallization begins within one h of exposure to the CO2 at temperatures and pressures as low as 75°C and 100 atm. The degree of crystallinity increases sharply as the CO2 pressure is raised from 100 to 300 atm but levels off thereafter. This behavior is likely due to a minimum in the Tg of the polycarbonate/CO2 mixture owing to the opposite effects of the pressure on the Tg of the polymer and on the equilibrium weight fraction of CO2 absorbed. Percent crystallinities of over 20%, comparable to that achieved using acetone or other organic liquids, have been obtained after 2 h exposure to supercritical CO2. Since polycarbonate degasses quickly and quantitatively at ambient temperature and pressure, the high Tg of bisphenol A polycarbonate can be regained in the crystallized material without further vacuum treatment.
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798 citations
TL;DR: The use of supercritical carbon dioxide as a processing solvent for the physical processing of polymeric materials is reviewed in this article, with an emphasis on available data and measurement techniques, the development of theory or models for a particular property, and an evaluation of the current state of understanding for that property.
Abstract: The use of supercritical carbon dioxide as a processing solvent for the physical processing of polymeric materials is reviewed. Fundamental properties of CO2/polymer systems are discussed with an emphasis on available data and measurement techniques, the development of theory or models for a particular property, and an evaluation of the current state of understanding for that property. Applications such as impregnation, particle formation, foaming, blending, and injection molding are described in detail including practical operating information for selected topics. The review concludes with some forward-looking discussion on the future of CO2 in polymer processing.
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182 citations
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165 citations