キトサンの吸湿性

概要

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The sorption of water vapor was studied for chitosan by a gravimetric method and the sorptive capacity and the mechanisms of the sorption were discussed.<BR>The equilibrium sorption isotherms for chitosans having different amine contents give sigmoidal curves in shape irrespectively of the fine structure. The chitosans have higher sorptive affinities toward water than cellulose. Since the BET plots give good straight lines up to 43% relative humidity, the BET mechanism is applied to analyse the data thus obtained. The value corresponding to a monolayer of adsorbed water is about 0.78 mol of water per a glucose unit of chitosan. It is considered from the clustering functions of Zimm and Lundberg and the thermodynamic analyses that clustering of water occurs little after the monolayer sorption. But the mechanism of the localized sorption approaches to the solution one as the temperature of sorption becomes higher. This may be due to the change in the higher-order structure of chitosan by the sorbed water. In the measurements of the density of wet-polymer samples by the use of a density gradient column composed of xylene-tetrachloromethane mixture, dry chitosan appears to sorb xylene preferentially.
公益社団法人高分子学会の論文