The influence of penetrant concentration on the diffusion and permeation of small molecules in polymers above tg

✍ Scribed by P. Meares

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 582 KB
• Volume: 29
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(93)90089-x

✦ Synopsis

The diffusion of fairly small organic molecules in polymers above their glass transitions is normally governed by Fick's law but with diffusion coetficients that are strongly, almost exponentially, increasing functions of penetrant concentration. Attempts to develop a comprehensive and quantitative theory of this phenomenon have extended over almost 40 years. The most satisfactory have made use of the concept of free volume. In this review the development of the free volume theory of diffusion in polymers is traced from its introduction up to the present time.

polymerization at high conversion. Although the transition from reaction to diffusion control has been reliably demonstrated, the analyses so far have been unable to predict when this should occur. Progress in this area might be aided if the diffusion coefficients of the reactive or high-energy species were expressed in terms of local composition and concentration.