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Gas permeabilities and permselectivity of photochemically crosslinked polyimides
Author(s) -
Liu Ye,
Ding Mengxian,
Xu Jiping
Publication year - 1995
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1995.070580301
Subject(s) - polyimide , benzophenone , irradiation , nitrogen , permeation , hydrogen , oxygen , materials science , oxygen permeability , permeability (electromagnetism) , polymer chemistry , chemistry , photochemistry , chemical engineering , composite material , organic chemistry , membrane , biochemistry , physics , layer (electronics) , nuclear physics , engineering
Abstract Photosensitive polyimide BTDA‐3MPDA was modified by UV irradiation. The structure of UV‐irradiated polyimides was investigated by FTIR and gel fraction measurements. The results showed that longer UV exposure time resulted in a higher extent of crosslinking. The gas permeabilities of hydrogen, oxygen and nitrogen through UV‐irradiated polyimides were characterized in a temperature range from 30°C to 90°C. Photocrosslinking resulted in a sharp decline in gas permeability for hydrogen, oxygen, and nitrogen through polyimide in the initial stage of photocrosslinking. Then, as the crosslinked benzophenone percentage amounted to 28–38% for hydrogen, 17–31% for oxygen and 3–28% for nitrogen, the gas permeabilities showed another sharp decline. Gas permselectivity increased significantly with the progress of photocrosslinking, and it can be adjusted in a wide range by controlling the extent of crosslinking. Arrhenius plots of gas permeability for hydrogen and oxygen through UV‐irradiated polyimides are straight lines; for nitrogen, however, change in the slope of the straight line is observed and activation energies for hydrogen and oxygen permeation show abrupt increases when crosslinked benzophenone percentage amounts to about 30%. UV‐irradiated polyimides with simultaneous high gas permeability and permselectivity make them ideal candidate materials for gas separation. © 1995 John Wiley & Sons, Inc.