Permeability and permselectivity of gases in fluorinated and non-fluorinated polyimides

Tanaka, Kazuhiro; Kita, Hidetoshi; Okano, Masaaki; Okamoto, Ken‐ichi

doi:10.1016/0032-3861(92)90736-g

Cited by 324 publications

(247 citation statements)

References 15 publications

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“…Films of 1,2-PB, PV AC, PS, PMA, and PBMA were cast from their benzene solutions onto glass plates, and dried at 323 K (300 K for PMA) for 20 h in vacuo. 9 6FDA-DAH Pl was prepared by the method described elsewhere, 10 and its films were cast from the dichloromethane solutions and dried at 373 K for 20 h in vacuo. Characterization of the films were carried out by the methods described in the previous paper.…”

Section: Experiments Almentioning

confidence: 99%

Correlation between Positron Annihilation and Gas Diffusion Properties of Various Rubbery Polymers

Okamoto

Tanaka

Katsube

et al. 1993

Polym J

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ABSTRACT:Diffusion coefficients D for CO2 and CH4 , their activation energies, E0 , and lifetime and intensity of ortho-positronium (o-Ps), , 3 and / 3 respectively, were measured for nine polymers at temperatures T from glass transition temperature T 8 up to T 8 + 70 K. For semicrystalline polymers, D and / 3 are corrected to give those in 100% amorphous samples, D, and / 3 ,., respectively. Average size of free volume holes probed by o-Ps, vh,P" is evaluated from , 3 using an empirical equation. According to the free volume model of diffusion, correlations between log(D,/T) and fractional free volumefand between E0 /RT and Tf-2 (df/dT) are tested, using WLF fractional free volumefwLF, vh,PJ3, and vh,Ps for f The correlations are better for vh,Ps than for vh,rJ3 . There is no correlation for fwLF· The volume fraction of free volume holes larger than the effective size of the penetrants, VF,dif, are evaluated by a proposed model from vh,Ps and volume fraction of 'free space,' VF, estimated by the method of van Kreveran and Bondi. The correlations are better for VF,dif than for VF and also for vh,Ps· The apparent good correlations for vh,Ps are ascribed to the correlation of it with V F,dif· KEY WORDS Diffusion Coefficient / Rubbery Polymer / Free Volume / Positron Annihilation/ ortho-Positronium / Carbon Dioxide/ Free Volume Distribution / Diffusion of penetrant molecules in polymers is a subject of great importance from the standpoint of membrane separation. Diffusion of penetrants in rubbery polymers is often interpreted by free volume theory. 1 -3 According to Fujita's formulation, 1 the diffusion coefficient, D 0 , at zero penetrant concentration is given by fractional free volume. The fractional free volume is generally expressed bywhere Aa and Ba are the parameters dependent on penetrant molecular size and shape, R is the gas constant, T temperature, and J

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Section: Experiments Almentioning

confidence: 99%

Correlation between Positron Annihilation and Gas Diffusion Properties of Various Rubbery Polymers

Okamoto

Tanaka

Katsube

et al. 1993

Polym J

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“…With the use of polymers as gas membranes for separation technology and PEM fuel cell electrolytes, the majority of the studies have focused on permeation of hydrogen [12][13][14][15][16][17][18][19] , with some groups also investigating the sorption characteristics of the polymers 18,20,21 . Fiber reinforced polymers are the leading candidate for hydrogen piping systems 6 , and polymers can be used as metal pipe and tank liners.…”

Section: Effect Of Hydrogen On the Mechanical Properties Of Polymersmentioning

confidence: 99%

Review on the effects of hydrogen at extreme pressures and temperatures on the mechanical behavior of polymers.

Hecht¹

2013

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The effects of hydrogen on the mechanics (e.g. strength, ductility, and fatigue resistance) of polymer materials are outlined in this report. There are a small number of studies reported in the literature on this topic, and even fewer at the extreme temperatures to which hydrogen service materials will be exposed. Several studies found little evidence that hydrogen affects the static tensile properties, long term creep, or ductile fracture of high density polyethylene or polyamide. However, there has been a report that a recoverable drop in the modulus of high density polyethylene is observable under high hydrogen pressure. A research need exists on the mechanical effects of hydrogen on the wide range of polymers used or considered for use in the hydrogen economy, due to the lack of data in the literature.

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“…In this project, we developed a membrane-based sour gas removal process using a new class of membrane material, a carbon molecular sieve (CMS) composite membrane, i.e., CMS membranes supported on commercial porous inorganic membranes as substrates. CMS membranes have been demonstrated in a variety of laboratory studies to be superior to polymeric membranes in terms of permeability, selectivity, and robustness [2][3][4][5][6][7][8][9][10][11][12][13][14][15][20][21][22][23][24]. In comparison to competing membrane technologies for natural gas upgrading, the CMS composite membranes have the potential to reduce both capital and operating costs.…”

Section: Introduction/application Backgroundmentioning

confidence: 99%

Gas Separations using Ceramic Membranes

Liu¹

2005

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Permeability and permselectivity of gases in fluorinated and non-fluorinated polyimides

Cited by 324 publications

References 15 publications

Correlation between Positron Annihilation and Gas Diffusion Properties of Various Rubbery Polymers

Correlation between Positron Annihilation and Gas Diffusion Properties of Various Rubbery Polymers

Review on the effects of hydrogen at extreme pressures and temperatures on the mechanical behavior of polymers.

Gas Separations using Ceramic Membranes

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