Permeation, diffusion, and solution of gases and water vapor in unplasticized poly(vinylchloride)

The transport behavior of a number of permanent gases of varying molecular size and of water vapor was studied in calendered films of unplasticized poly(vinylchloride). Permeabilities, diffusivities, and solubilities were measured over a range of temperatures traversing the glass transition. A discrete change in the activation energy for diffusion was observed for Ar and Kr. No change in the activation energy for diffusion for He, Ne, CH 4 , N 2 , CO 2 , O 2 , and H 2 O was observed, as the glass transition was traversed. This appeared to be the first polymer system studied in detail in which the change in activation energy for diffusion is related to penetrant size rather than to a unique dependence upon polymer fine structurej