Dependence of permeability coefficient on concentration

For a first approximation, the simple expressions in Eqs. (9-1), (9-2) and (9-5) can be used for calculating the permeation of a given organic substance. However, the applicability is to some degree considerably reduced, depending on the molecular structures and their related properties. Various deviations from the behavior of simple gases complicate the calculated estimation of an organic substance s permeability. 

For the same reasons, the published data for S, D and P values can be plagued to some degree by serious measurement errors. In view of the ranges of the three param- 

Some measured values, D and K, (Koszinowski 1986, and Koszinowski and Pirin-ger, 1990) are contained in Table 9-7. These data deal mainly with the partition coefficients of hydrocarbons, alcohols, phenols and a series of aromas between polyolefins and a liquid phase (ethanol, methanol) as well as diffusion coefficients of these substances in the polymer. 

Thble 9-7 Diffusion coefficients of organic compounds in LDPE and partition coefficients between LDPE und methanol or ethanol( ) at 23 °C. 

Topanol (l,l,3-tris(2-methyl-4-hydroxi-5-tert-butylphenyl) butane) C37H5203 0.00060 0.00031 0.054 

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