Characterisation of nonporous membranes

Nonporous membranes are used to perform separations on a molecular level. However, rather than molecular weight or molecular size, the chemical nature and morphology of the polymeric membrane and the extent of interaction between the polymer and the permeants are the important factors to consider. Transport through nonporous membranes occurs by a solution-diffusion mechanism and separation is achieved ei er by differences in solubility and/or diffusivity. Hence such membranes cannot be characterised by the methods described in the previous section, where the techniques involved mainly characterised the pore size and pore size distribution in the membranes. The determination of the physical properties related to the chemical structure is now more important and in this respect the following methods will be described  

Since transport proceeds mainly via the amorphous regions, it is very inq)ortant to know 

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