Zimm-Lundberg cluster theory

In spite of the composite nature of the stratum corneum, its water sorption isotherm is qualitatively identical to those of the more simple protein systems shown, suggesting that water interacts predominately with the protein components of the corneum. This conclusion is supported further by the results of chloroform-methanol (3/1 by volume) extraction which removed as much as 25% of the original dry weight (lipids and low molecular weight water-soluble components) but did not quantitatively alter the isotherm in the low relative humidities (18). The application of the Zimm-Lundberg cluster theory (56, 57) to the isotherm yields additional information as to the state of the sorbed water in the corneum. The tendency of water to cluster is expressed in this theory by the cluster function CiGn ... 

Table 5.2 Comparison of specific surface areas calculated from the ascending branch of the water isotherms of selected cellulosic materials by the BET theory, the ct procedure and the Zimm and Lundberg (ZL) cluster theory.

Thus it is clear that the term "clustering" can be used in a variety of situations, and is not precisely defined. In the present case, it will be used in the context of the statistical thermodynamic treatment of binary solutions developed by Zlmm ( ) and Zimm and Lundberg ( ), which provides a calculation of a cluster integral, and which can be extended to specify a cluster size for each component. In describing the role of the "clustering" theory in relationship to previously developed solution theories, such as the widely used Flory-Huggins theory ( ), Zimm and Lundberg point out that "Our considerations are not intended as a replacement for the previous theories, but as... 

Despite the fact that there have been many attempts to correlate the sorption behavior of water with the microstructure of the polymer matrix, very few studies have been attempted to correlate water sorption with localized water structure that is induced by the microstructure of the polymer [41]. Zimm and Lundberg [42] have carried out this type of analysis by a cluster theory. 

The Zimm (or Zimm and Lundberg ) theory of solvent clustering became a popular tool for the estimation of solvent clustering in solvent (l)-polymer (protein) (2) systems. 

Gaa may be determined from equilibrium sorption data as a ftinction of penetrant partial pressure. Based on the theory of Zimm and Lundberg (53), the cluster function given by ([Pg.1298]

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