Improved measurement device for vapor permeation and pervaporation

Abstract

A precision measurement method of vapor permeability through polymer membranes was developed and tested for cellulose acetate membranes. An apparatus with a differential transformer and a float on the liquid source could precisely measure the vapor permeation rate as well as pervaporation flux by sensing the level of the source liquid. The permeation rates with vapor feed and liquid feed of water, alcohols, and organic solvents were measured for silicone rubber and cellulose acetate, cellulose triacetate, and water-soluble cellulose acetate membranes. The measured vapor permeability directly predicted the pervaporation flux through silicone rubber. In the case of swollen material due to the feed liquid, the vapor permeability was not a controlling property of the pervaporation flux, but became an analysis base for it.

Networks from α,ω-Dihydroxypoly(dimethylsiloxane) and (Tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane: Surface Microstructures and Surface Characterization

“…Network formation requires the diffusion of water and/or ethanol from the evolving network. The permeation rates of ethanol and water through PDMS are relatively high . While the diffusion of small molecules is relatively rapid, the diffusion of macromolecular species is impeded by viscosity buildup in the evolving network.…”