Low‐pressure plasticization of PEBAX 2533 membrane by carbon dioxide

Abstract

AbstractPEBAX 2533 membrane is used to investigate plasticization by carbon dioxide (CO2) at low pressure. To reduce complex interaction caused by hydrostatic pressure and competitive sorption, a new experimental technique named the “Rest test” is presented. In the Rest test, the membrane is exposed to permeation of CO2 at 4 bar for 30 min and then put to rest for up to 12 h with residual CO2 after ventilation. When the membrane rests more than 9 h with residual CO2 after the permeation, the permeability increases by, at least, 50%. Permeation of CO2 is the prerequisite condition of permeability increase during the rest. Permeability increase in the Rest test is improved by permeate side purge and prolonged rest period. Fugacity and sorption of leftover CO2 during the rest are the main factors inducing the permeability increase, whereas the permeability increase is suppressed by higher feed pressure and longer CO2 permeation time, indicating the influence of hydrostatic pressure. The Rest test cannot increase the permeability of glassier PEBAX 1657. The findings and relevant factors suggest that low‐pressure plasticization during the rest is a potential source of the permeability increase.