Co-polyimide hollow fiber

R. Liu, X. Qiao, and T.-S. Chung. The development of high performance P84 co-polyimide hollow fibers for pervaporation dehydration of isopropanol. Chem. Eng. ScL, 60(23) 6674-6686, December 2005. 

Case study H2 Separation from H2/N2 and H2/CO Mixtures with co-polyimide Hollow Fiber Modules... 

Kusuki and co-workers (1997) and Okamoto et al. (1999) formed CMS membranes from asymmetric polyimide hollow fibers formed from BPDA and aromatic diamines. The authors pretreated the fibers by heating to 400°C in atmospheric air for 30 min. The pretreatment was necessary to maintain the asymmetric structure of the preeursors. Otherwise, the precursor softened and the carbon membranes had low separation performance. 

Dual-layer polyethersulfone (PES)/BTDA-TD1/MD1 co-polyimide (P84) hollow fiber membranes with a submicron PES-zeolite beta mixed matrix dense-selective layer for... 

Wang KY, Chung TS, Rajagopalan R. Dehy- [109] drafion of tetrafluoropropanol ( IFF) by pervaporation via novel PBI/BTDA-TDl/MDl co-polyimide (P84) dual-layer hollow fiber membranes. J Membr Sci 2007 287(l) 60-6. 

Barsema, J.N., Kapantaidakis, G.C., van derVegt, N.F.A., Koops, G.H. and Weshng, M. 2003. Preparation and characterization of highly selective dense and hollow fiber asymmetric membranes based on BTDA-TDI/MDI co-polyimide. / 216 195-205. 

The work of Pinnau and co-workers with asymmetric films was the first to show dramatic time-dependent gas transport properties (127,128). Later, Pfromm and co-workers showed similar behavior in free-standing polyimide and polysul-fone films (129). Figure 34 shows that for a 0.5-/xm thick polyimide film, the N2 permeability decreases by approximately 50% over a 6000-h period, while the He/N2 selectivity increases by approximately 25% in the same time period. The decrease in permeability is not nearly as dramatic for the thick films. Rezac and co-workers (130) and McCaig and co-workers (131) saw similar effects in pol5dmide/ceramic and polycarbonate/ceramic composite membranes, respectively. Chung and Teoh observed the same effects in asymmetric hollow fiber gas separation membranes (132). 

The earliest report on CMS membranes obtained from hollow fiber polymeric membranes appears to be from Koresh and Soffer (1983) and Soffer et al. (1987). By comparing CMS membranes derived from different polymeric membranes, Jones and Koros (1994a) found that the ones from aromatic polyimides yielded the best separation and mechanical properties. The polymers tested by Jones and Koros were cellulose acetate, polyaramides, and polyimides. Polyfurfural alcohol was used by Foley and co-workers (Foley, 1995 Shiflett and Foley, 1999 Strano and Foley, 2002). A comparison of the O2 permeances and O2/N2 selectivities showed that the CMS membrane from polyimide was indeed much better than that from polyfurfural alcohol, as will be seen shortly. 

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