A determination of solubility coefficient values determined by gravimetric and isostatic permeability techniques
The solubility coefficient (s) values for ethyl acetate in three heat sealant polymer membranes (LDPE, LLDPE and ionomer) were determined over a range of permeant vapour concentrations by a gravimetric procedure and an isostatic permeability technique. The respective solubility coefficient values obtained by the two methods were found to be in good agreement, with no statistically significant difference observed as a function of vapour activity. This agreement suggests that the solubility coefficient values obtained were independent of permeant vapour activity, and the sorption process followed a Henry's law relationship over the vapour concentration range evaluated. Comparison of the solubility coefficient values obtained by the gravimetric and isostatic permeability techniques showed reasonably good agreement over the vapour concentration range considered, with the S values obtained from permeability experiments being approximately 25% higher than those obtained from sorption measurements. Because of the procedural differences between the gravimetric and isostatic permeability techniques, this agreement is considered to be within acceptable limits. For the gravimetric technique, the solubility coefficient value is determined directly from the steady-state portion of the sorption profile curve, while the solubility coefficient value obtained from the permeability experiment is derived from transient state data. Copyright © 2000 John Wiley & Sons, Ltd.
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Document Type: Research Article
Publication date: 2000-07-01
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