Properties determining mass transfer in polymeric systems

Permeation and dissolution are the main processes determined by diffusive mass transfer. Permeation of polymers by small molecules depends on their solubility and diffusivity. For both quantities reasonable estimations are possible if some basic data of the permeating molecules (e.g. critical temperature and collision diameter) and of the polymer (structure, glass transition temperature, crystallinity) are known. For the estimation of the permeability of thin layers (films) an additive quantity, the permachor, is available. 

Dissolution of polymers is controlled by processes of diffusion and convection. The rate of diffusion may be estimated from the intrinsic properties of the polymer and the Reynolds number of the dissolving liquid. 

In this chapter the diffusive mass transfer, as observed in practical applications of polymeric systems will be discussed. Three categories will be considered. 

The second category is that of the mass transfer of heavier organic vapours and liquids as occurs in polymeric constructions such as plastic containers and bottles. In this case the situation is more complicated very often there is stronger interaction between penetrant and polymer. The performance of useful and repeatable experiments and the acquiring of quantitative knowledge can be very difficult. 

The last category of mass transfer problems is the dissolution of polymers by liquids. The study of this category is still in its infancy. 

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Properties Determining Mass Transfer In Polymeric Systems... 

D.W. Van Krevelen, Properties of Polymers, Ch 18. Properties Determining Mass Transfer in Polymeric Systems, p. 861, Elsevier Science B.V., Amsterdam, The Netherlands, 1997. 

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