Transport Properties of Polymeric Mixtures

Gapillary column IGC was used to determine the diffiisivity, solubility and transport properties of various test solutes in polymers and polymeric mixtures. These 

Equation (10.30) is an extension of an equation introduced by Pawlisch [63,64], by addition of the (1 - y) term in the a parameter [36]. This expresses the change in velocity with concentration (sorption effect) the y parameter is equal to zero at infinite dilution. 

The Pawlisch model [63] was applied, for example, to calculate the partition coefficient and diffusion coefficients of a series of solvents in PMMA-co-BMA (poly(methyl methacrylate-co-butyl methacrylate)) at infinite dilution [66]. Values of K and Dp that best fitted the experimental data were found, and the model predicted perfectly the system behavior. The Vrentas-Duda free volume theory was found to correctly correlate diffusion data above Tg. 

Zhang et al. [71] employed a packed-column IGC technique to determine the activity coefficients and diffiisivities of small molecules in phenol resins. For this, they applied the Romdhane-Danner approach for data analysis, and the Braun-Guillet approach to determine the thickness of the polymer layer on the support Subsequently, the authors reported that the IGC-derived difiusivity data were consistent with the theoretical data obtained from the Romdhane-Danner approach, and might be further used to predict the temperature- and concentration-dependence of diffusivity by the free volume theory. 

Cava et al. [72] applied the IGC technique to examine the effect of moisture on the transport properties of several low-molecular-weight alcohols through high-barrier copolymers. The apphcation of Romdhane-Danner methods allowed an estimation of the diffusion coefficient Dp at different humidity conditions, that is, at various values of relative humidity (%RH). The sorption of water by the 

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