Physical aging of polystyrene films tracked by gas permeability

Polymer ◽  
2013 ◽  
Vol 54 (2) ◽  
pp. 873-880 ◽  
Author(s):  
Thomas M. Murphy ◽  
B.D. Freeman ◽  
D.R. Paul
Keyword(s):  
Physical Aging ◽  
Gas Permeability

Responses of 6FDA-based polyimide thin membranes to CO2 exposure and physical aging as monitored by gas permeability

Polymer ◽  
2011 ◽  
Vol 52 (24) ◽  
pp. 5528-5537 ◽  
Author(s):  
Lili Cui ◽  
Wulin Qiu ◽  
D.R. Paul ◽  
W.J. Koros
Keyword(s):  
Physical Aging ◽  
Gas Permeability ◽  
Thin Membranes

scholarly journals Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

2021 ◽  
Author(s):  
Faiz Almansour ◽  
Monica Alberto ◽  
Rupesh S. Bhavsar ◽  
Xiaolei Fan ◽  
Peter M. Budd ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Separation Performance ◽  
Aging Effects ◽  
Methanol Vapor ◽  
Alcohol Vapor ◽  
Industrial Level ◽  
Vapor Treatment

AbstractPhysical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO2 and CH4 (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO2 permeability > 7000 barrer.

Physical aging of 6FDA-based polyimide membranes monitored by gas permeability

Polymer ◽  
2011 ◽  
Vol 52 (15) ◽  
pp. 3374-3380 ◽  
Author(s):  
Lili Cui ◽  
Wulin Qiu ◽  
D.R. Paul ◽  
W.J. Koros
Keyword(s):  
Physical Aging ◽  
Gas Permeability ◽  
Polyimide Membranes

Physical aging of ultrathin glassy polymer films tracked by gas permeability

Polymer ◽  
2009 ◽  
Vol 50 (23) ◽  
pp. 5565-5575 ◽  
Author(s):  
Brandon W. Rowe ◽  
Benny D. Freeman ◽  
Donald R. Paul
Keyword(s):  
Polymer Films ◽  
Physical Aging ◽  
Glassy Polymer ◽  
Gas Permeability

scholarly journals Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1241 ◽  
Author(s):  
Silvio Neumann ◽  
Gisela Bengtson ◽  
David Meis ◽  
Volkan Filiz
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Time Lag ◽  
Polymer Chains ◽  
Separation Performance ◽  
Polymer Backbone ◽  
Cross Linkage ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

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