Petropoulos model, glassy polymer transport

The predicted effect of du mode sorption on the time lag and permeability vras derived by Paul using the total immobilization transport model and experimentally verified by Paul and Kemp using molecular sieves embedded in a silicone mbber. This was an excellent model system which fulfilled the postulate of complete inunobilization of the Langmuirian mode penetrant. The possibility that gas molecules sorbed in the Langmuirian mode may not necessarily be completely immobilized in glassy polymers was first raised by Petropoulos in 1970 Equations were developed and the possibility of these being used to check the assumption of immobilization by sorption and permeation data were described. The relaxation of the... 

The following three multicomponent transport models have been used to explain the depression of the permeability of a component in a mixture relative to its pure component value (Fig. 21) the Petropoulos model and the competitive sorption model, both of which assume that direct competition for diflfiisive pathways within the glass is negligible, and a more general permeability model in which direct competition can occur between penetrant molecules for both sorption sites and diffusion pathways. All three of the models presented here are based upon the framework of the dual-mode model. It is worth mentioning that the site-distribution model has recently been extended to accoimt for diffusion (98) and that free volume models exist for transport in glassy polymers (99). 

Petropoulos J H, On the dual mode gas transport model for glassy polymers ,... 

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