Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1991-08-01
1995-05-09
Edwards, N.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428376, 428395, 428397, 428398, D02G 300
Patent
active
054138523
ABSTRACT:
Asymmetric hollow fibers of SIXEF.TM.-Durene, a polyimide made from 2,2-bis[3,4-dicarboxyphenyl] hexafluoropropane dianhydride and 2,3,5,6-tetramethylphenylene diamine monomers, and a process for making such fibers. These uncoated fibers have a separation factor that exceeds 4 for oxygen and nitrogen and a permeance of at least about 50 ppm cc(STP)/(sec cm.sup.2 cm-Hg). A polymer dope comprising SIXEF.TM.-Durene in a solvent system containing N-methyl-2-pyrrolidone ("NMP") and an organic acid such as propionic acid ("PA") is prepared by polymerizing the polyimide monomers in NMP to form a polyamic acid polymer and imidizing this polymer using the acid anhydride. Water released from the polymer in the imidization reaction converts the anhydride to the organic acid. The dope is wet-spun into hollow fibers using a core solvent such as PA or glycerine; the fibers are coagulated in water.
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Chung Tai-Shung
Kafchinski Edward R.
Vora Rohitkumar H.
Edwards N.
Hoechst Celanese Corp.
Mazzarese Joseph M.
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