Capillary condensation mechanism for gas transport in fiber reinforced poly (ether-b-amide) membranes

Abstract

One of the most important shortcomings of the polymeric membranes in comparison with inorganic membranes is the trade-off between permeability and selectivity. Gas permeability in inorganic membranes follows different mechanisms including capillary condensation mechanism. The aim of present study was improving the polymeric membranes performance by introducing capillary condensation mechanism for the gas transport similar to that observed in the inorganic membranes. Capillary condensation of gases needs a continuous diffusion pathway, therefore in the present study short glass wool fibers (with a micro size in diameter and millimeter size in length) were chosen as a proper alternative instead of nanoparticles. Short glass wool fibers present proper dispersion in the Pebax matrix as a result of its good compatibility with polymer segments. Gas permeability behavior in such composite membranes was assisted using pure CO2, CH4 and N2 gases. Obtained results demonstrated that gas permeability behavior in the short fiber reinforced composite membranes is depends on the fiber content. At lower content of the fiber, such reinforcement causes simultaneous increment in gas permeabilities in a way that 62.37%, 32.12% and 50.71% increase in permeability was observed for CO2, CH4, and N2 respectively. But at higher content due to formation of more continuous interface, capillary condensation was appeared for more condensable gas (CO2) which results in 17.65% reduction in its permeability. Based on the results the using of short fiber instead of nanoparticles in polymeric membranes can be more beneficial in performance and economic point of view.