Glassy polymer membranes aging

Membranes from Glassy Polymers Physical Aging 69... 

D.L. Gin, R.D. Noble, Ending aging in super glassy polymer membranes, Angewandte Che-mie 126 (2014) 5426-5430. 

Poly(4-methyl-2-pentyne) [PMP] is a glassy, disubstituted, purely hydrocarbon-based polyacetylene. PMP has a density of only 0.78 g/cm and a high fractional free volume of 0.28. The polymer has very high hydrocarbon permeabilities for example, the /i-butane permeability of PMP in a mixture of 2 mol% n-butane in methane is 7,500 X lO l cm3(STP) cm/cm2 s cmHg at 25 C. In contrast to conventional, low-free-volume glassy polymer membranes, PMP is significantly more permeable to n-butane than to methane in gas mixtures. In this paper, we present the gas permeation properties of PMP in mixtures of -butane with methane. The mixed-gas permeation and physical aging properties of PMP are compared to those of poly(l-trimethylsilyl-l-propyne), the most permeable polymer known. 

Effect of aging on the permeability and molecular motion of the membranes of PMSP, poly(TMSP-co-PP) and blend of PMSP/PPP Glassy polymers, such as PMSP, are nonequilibiium materials and their permeation and sorption properties drift over time as thermally driven, small-scale polymer segmental motions cause a relaxation of nonequilibrium excess free volume. The microcavities of large size which are present in PMSP membrane have been considered to be responsible for the decay of C h and the gas permeability (4). Therefore, it is possible to stabilize the gas permeability by control the C by copolymerization or blending with the other acetylene derivatives such as PP and PPP, respectively. 

The ability of limiting aging phenomena in high free volume glassy polymers is a recent discovery for hybrid membranes and can open up a new branch of study for this polymers family. If selectivity enhancement via the sieving mechanisms and antiaging properties of the fillers can be coupled with the high transmembrane flux offered by the polymer phase, superior separation features can be achieved. 

Rowe, B.W., Freeman, B.D., Paul, D.R. Influence of previous history on physical aging in thin glassy polymer films as gas separation membranes. Pol)nner 51(16), 3784—3792 (2010)... 

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