Measurement of Co2 Permeability in Polymer Films

Abstract

A simple and sensitive method for measuring CO₂ permeability in polymer films has been developed. The method is based on the use of ¹⁴CO₂. At time zero ¹⁴CO₂ is injected on the high pressure side of the cell. Permeation is monitored with a Geiger counter which senses ¹⁴CO₂ on the low pressure side of the cell. The counts/time on the low pressure side are proportional to the total concentration of CO₂ which has diffused through the film. With the known source concentration the volume-time curve is constructed and the permeability and time lag are calculated. The system sensitivity as it is presently configured is on the order of 10^-15 em³(STP).cm/cm².sec.cm Hg. Results are presented for a measurement of a 0.025 cm polycarbonate film.

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