Permeation of gases through modified polymer films III. Gas permeability and separation characteristics of gamma-irradiated teflon FEP copolymer films |
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Authors: | Robert Y M Huang Peter J F Kanitz |
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Institution: | 1. Department of Chemical Engineeringc , University of Waterlooc , Waterloo, Ontario, Canada;2. Department of Chemical Engineeringc , University of Waterlooc , Waterloo, Ontario, Canada;3. Engineering Technology Division, Seneca College of Applied Arts and Technology , Willowdale, Ontario, Canada |
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Abstract: | A study has been made of the diffusion, solubility, and separation of nitrogen and methane gases at temperatures ranging from 15° to 50°C in a series of Teflon FEP copolymer films which were irradiated by γ rays in air and under vacuum. The irradiated films were subjected to postirradiation treatment temperatures above and below the glass I transition temperature of the copolymer. The effect of radiation on crystallinity and cross-linking was examined by density, thermal, and tensile strength measurements. Diffusion and permeability coefficients of both gases decreased with irradiation dose but solubility coefficients were not greatly affected. Nitrogen-methane separation factors for vacuum-irradiated films increased with irradiation dose, but little change was observed for the air-irradiated films. Chain scission appeared to be the predominant reaction in air-irradiated films whereas both cross-linking and chain scission occurred in vacuum-irradiated films depending on post-irradiation heat-treatment conditions. The permselectivity of the Teflon FEP films was increased by γ irradiation but this was achieved at the expense of the permeation rate. |
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Keywords: | Poly(oxyalkylene) block copolymers SAXS Avrami model Transitions |
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