CED and Solubility Parameters

The unique properties of polymers can be attributed to the fact that polymer segments are held together by covalent bonds in one direction but by secondary bonds in the other two. A measure of the strength of secondary bonds is given by the CED  

AEv is the molar energy of vaporization Vi is the molar volume of the liquid 

Eor small molecules, AEy can be measured by conventional means. The energy necessary to separate molecules from one another from the close spacing typical of the liquid state to the distant spacing of the vapor is evaluated directly by calorimetric methods or indirectly by measuring the vapor pressure p as a function of absolute temperature T. The Clapeyron equation can be used to extract an enthalpy of vaporization AH- 

Vg and V, are the molar volumes of the compound in the vapor and liquid, respectively, at temperature T 

The solubility parameter introduced in Section 2.5 is the square root of CED. 

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