DEVELOPMENT OF A DEFECT-FREE 6FDA-DURENE ASYMMETRIC HOLLOW-FIBER AND ITS COMPOSITE HOLLOW FIBERS

We have developed 6FDA-durene polyimide and poly(4-vinylpyridine) (PVP )/6FDA-durene composite hollow fibers. The 6FDA-durene fiber was defec t-free and had a selectivity of 4.3-5.1 for O2/N2. It had an average p ermeance for O2 of approximately 240 x 10(-6) cm3 (STP)/cm2 s cmHg and its dense layer thickness was approximately 2000-3000 mum. The dense layer location was at the outer surface. This fiber was wet-spun direc tly from an in-situ imidization dope consisting of 14.94 wt% 6FDA-dure ne in a (70.24/21.5/7.51/0.75) N-methyl-2-pyrrolidone (NMP)/propionic acid (PA)/beta-picoline/propionic anhydride solvent mixture. The fiber diameter was approximately 500 mum with a wall thickness approximatel y 50-75 mum. The PVP/6FDA-durene composite fiber had a selectivity of 6.9 for O2/N2 and a permeance for O2 of 14.5 x 10(-6) cm3 (STP)/cm2 s cmHg. The newly developed technology suggests, for the first time, tha t a defect-free hollow fiber can be produced from a modified Lewis aci d: base complex dope. Compared to most other conventional hollow fiber fabrication processes, our approach has many advantages because that (1) it is simpler and more economical, (2) spins fibers at low tempera tures, (3) employs a dope directly from polymerization, and (4) requir es no secondary operations, such as silicone coating and curing.