Gas Permeation Property of 6FDA-mPDA and Its Asymmetric Hollow Fiber Membranes

Abstract

Abstract:

2,2′-Bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride(6FDA)-1, 3-phenylenediamine(mPDA) polyimide was synthesized by chemical imidization in a two-step procedure. The density of the polymer dense membrane, the fractional free volume and the glass transition temperature were measured. The ultra-thin hollow fiber membranes with a dense skin were fabricated with different air gap. The hollow fiber membranes have an O₂ permeance of 19.10 GPU and a CO₂ permeance of 106.34 GPU with the O₂/N₂ selectivity of 5.99 and the CO₂/CH₄ selectivity of 82.00 at 25 ℃, 0.5 MPa. The calculated thickness of the dense skin based on O₂ permeance is 96 nm. The temperature effect on the gas separation performance was investigated. The permeances of the O₂, N₂, CH₄ and CO₂ increase with an increase in temperature, while the selectivities of O₂/N₂ and CO₂/CH₄ decrease. The physical aging phenomenon of the asymmetric hollow fiber membranes spun with different air gap distances was investigated. The results show the permeance of the ultra-thin membranes sharply decreases and the selectivity increases. And the thickness of the dense skin affected the aging behavior.

Key words: Polyimide, Asymmetric hollow fiber membrane, Air gap, Physical aging

TrendMD:

DING Xiao-Li, CAO Yi-Ming*, WANG Li-Na, ZHAO Hong-Yong, JIE Xing-Ming, ....... Gas Permeation Property of 6FDA-mPDA and Its Asymmetric Hollow Fiber Membranes[J]. Chem. J. Chinese Universities, 2009, 30(6): 1240.

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