Measurement of the infinite dilute activity coefficients and diffusion coefficients of small molecule solvents in cross-linked polyvinyl alcohol by inverse gas chromatography

Molecular activity and diffusion coefficients of solvents are important and find wide range of applications to analyze in many problems including polymers, such as polymerization, separation, devolatilization, vacuum/gas stripping and drying. The polyvinyl alcohol (PVA) is a hydrophilic polymer membrane material, which was used extensively in the pervaporation process for dehydration. But due to its strong hydrophilic characteristic, it often occurs swelling when the water through the PVA membrane. In order to prolong the life of the PVA membrane and enhance the separation factor of the membrane, the process of cross-linking of PVA is necessary. In this work, a packed column IGC technique is adopted for determining the activity coefficients and diffusion coefficients of several solvents in polymers. The retention time and peak area of solvents is determined over a variety of flow rates at a constant temperature as well as over a variety of temperatures at a fixed flow rate. The infinite dilute diffusion coefficients of water, methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol in cross-linked PVA are reported. Those data will be useful in a study of the mechanism of small molecules transferring in cross-linked PVA polymer and will avail in the prediction of the separation results for various mixtures.