The flow of gases through high polymer films in equilibrium with sorbed vapors

A new apparatus is described for the measurement of the permeability constants of polymer—vapor film systems to atmospheric gases. The permeability constants of regenerated cellulose to oxygen, nitrogen, and carbon dioxide were found to increase rapidly and nonlinearly with increasing relative humidity. The permeability constants of polyethylene to oxygen and nitrogen were found to increase in a like manner with increasing relative pressures of n‐hexane and carbon tetrachloride. In the case of the polyethylene—organic vapor and gas systems the activation energy for the permeation process appears to be independent of sorbed vapor concentration. Furthermore, it was found that the permeability constants of the polymer—vapor films increased linearly with sorbed vapor concentration. A theory based on an analogy with electrical conductivity is proposed to explain the form of this relationship. The theory appears to give good quantitative agreement for the polyethylene—hexane—oxygen system, but further experimental data are needed to establish the generality of the theory.