Plasticization behaviorofpolymericmembranes,inpresenceofasecondcomponentinthefeedisdif-
ferent fromplasticizationofpureCO2 due tocompetitivesorption.Thisstudyfocusedonamathematical
model derivedforpermeationofmixedgasesinglassypolymersconsideringtheplasticizationcase.It
wasassumedthatdiffusioncoefficient forallcomponentswereexclusivelyafunctionofplasticizing
component. Inthisstudy,thepartialimmobilizationmodelwasemployedtodeterminefractionof
mobile sorbedgases.ThismodelaccuratelypredictedthepermeationbehaviorofCO2asplasticizerand
N2 inpresenceofplasticization.Themodelparameterswerecalculatedby fitting experimentaldatafrom
literature.Plasticizationparameter(?) decreasedforbothCO2 and N2 by increasingfractionofN2 in the
feed. Itmeansthatplasticizationofglassypolymerswassuppressed.Thisdecreasewascausedby
competitivesorptionbetweenCO2 and N2. IndeedN2 in thefeedactsasananti-plasticizer.Inaddition,
permeances ofthefeedgascomponentsweredeclinedincomparisontopuregases,whichmightbe
attributed toreductionofsorptionandoccupyingLangmuirsiteswiththesecondcomponent.The
proposed modeliscapableofgivingausefultooltoenhanceourknowledgerelatedtopermeabilityand
selectivity behaviorofmixedgassystemsinglassypolymericmembranes.