Gas transport property of homo- and copolyimides from isomeric thiaphthalic dianhydride and oxydianiline

✍ Scribed by Yuesheng Li; Mengxian Ding; Jiping Xu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 138 KB
• Volume: 63
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970328)63:13<1821::aid-app14>3.0.co;2-0

✦ Synopsis

Gas transport properties of homo-and copolyimides prepared from 3,3,4,4-and 2,2,3,3-thiaphthalic dianhydride ( p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former is lower than that of the latter. The permeability coefficients of m-TDPA-ODA to H 2 , CO 2 , and O 2 are more increased by 48, 69 and 75%, at 30ЊC and 10 atm, respectively, than those of p-TDPA-ODA; but the permselectivities of m-TDPA-ODA for H 2 , CO 2 , and O 2 toward N 2 are more decreased by 33, 77, and 26%, respectively, than those of p-TDPA-ODA. The permeability coefficients and the diffusion coefficients of the copolyimides can be described by the following equations: log P Å F p log P p / F m log P m and log D a Å F p log(D a ) p / F m log(D a ) m , respectively. The variation of the permselectivity is controlled predominantly by diffusivity selectivity. These observations are interpreted in terms of variations in the fractional free volume of polyimides.