Gas permeability and permselectivity of photochemically crosslinked copolyimides

✍ Scribed by Ye Liu; Caiyuan Pan; Mengxiang Ding; Jiping Xu

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 129 KB
• Volume: 73
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19990725)73:4<521::aid-app8>3.0.co;2-p

✦ Synopsis

A series of copolyimides were prepared from 2,4,6-trimethyl-1,3-phenylenediamines (3MPDA), 3,3Ј,4,4Ј-benzophenone tetracarboxyl dianhydride (BTDA), and pyromellitic dianhydride (PMDA). Modification of the copolyimides by ultraviolet irradiation were carried out. Gas permeabilities of H 2 , O 2 , and N 2 through the copolyimides and photochemically crosslinked copolyimides were measured at temperatures from 30 to 90°C. The relationships between gas permeabilities and temperature are in agreement with the Arrhenius equation. The structure of photochemically crosslinked copolyimides were characterized by Fourier transform infrared and gel measurement methods. Linear relationships between both log P and E p and the volume fraction of PMDA-3MPDA exist. Photochemically crosslinking modification result in a decrease in gas permeability and an increase in E p and ␣(H 2 /N 2 ) for all the copolyimides. For H 2 /N 2 separation, photochemically crosslinked copolyimides are of higher gas permeabilities and permselectivities simultaneously than normal polyimides.