The permeation of gases through modified polymer films. IV. Gas permeability and separation characteristics of graft copolymers of polyethylene and teflon FEP films

Abstract

AbstractThe effects of grafting styrene and acrylonitrile onto polyethylene and Teflon FEP films on their gas permeation and separation properties were investigated. The time‐lag method was used to determine the permeability, diffusion, and solubility coefficients of nitrogen and methane gases in the grafted films. The separation factors of nitrogen—methane gas mixtures were measured by gas chromatography. Structural and morphologic changes in the modified films were examined by density, differential scanning calorimetry, and infrared measurements. Attempts were made to relate these changes to the gas permeation and separation characteristics of the films. Modification by graft copolymerization resulted in slightly improved separation factors; however, the permeability and diffusion coefficients decreased. The experimental permeability and diffusion coefficients for gas mixtures were in good agreement with those of the pure components and could be predicted by single gas permeability and diffusion coefficients.