Isotope effect in gas transport. I. Measurement of the free volume element in four polymers above the glass transition temperature
✍ Scribed by Ziegel, K. D. ;Eirich, F. R.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1970
- Tongue
- English
- Weight
- 663 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0449-2978
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✦ Synopsis
Abstract
The experimental observation of an isotope effect in diffusive gas transport across polymeric films is reported. The differences in energies of transport between hydrogen and deuterium are used to estimate the effective dimensions of characteristic minima or “wells” in the potential energy surface of rubbery polymers. The size of a well, determined by assuming it to be a cubical cavity, is interpreted as the effective free volume element v~f~, as measured by the hydrogen molecule probe. Estimations are made of the entropy of activation and “jump distance” for the hydrogen diffusion process based on v~f~ values and experimentally determined pre‐exponential factors.