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- Johansson, Hans-Olof, et al.
(författare)
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Experimental and Theoretical Study of Phase Separation in Aqueous Solutions of Clouding Polymers and Carboxylic Acids
- 1993
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 26:17, s. 4478-4483
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Tidskriftsartikel (refereegranskat)abstract
- The phase behavior of different carboxylic acids/nonionic polymer/water systems has been studied. The carboxylic acids investigated are acetic acid, propionic acid, and butyric acid. The polymers used are a linear random copolymer of ethylene oxide and propylene oxide (UCON) and ethyl(hydroxyethyl)-cellulose (EHEC). These polymers display a lower critical solution temperature (LCST) in water. The decrease of the polarity in the carboxylic acids as the carbon chain increases causes a decrease of the LCST of the system carboxylic acid/polymer/water. As a consequence of this the two-phase region expands. The experimentally determined phase diagrams can qualitatively be described and compared with a theoretical model, based on Flory-Huggins theory of polymer solubility. The cloud-point temperature of the systems decreases as the difference between the effective interaction of polymer-cosolute and cosolute-water increases.
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