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Gas permeability and permselectivity of polyimides prepared from phenylenediamines with methyl substitution at the ortho position
Author(s) -
Liu Ye,
Pan Caiyuan,
Ding Mengxiang,
Xu Jiping
Publication year - 1999
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199909)48:9<832::aid-pi215>3.0.co;2-d
Subject(s) - substitution (logic) , materials science , semipermeable membrane , permeability (electromagnetism) , chemical engineering , polymer chemistry , chemistry , composite material , organic chemistry , membrane , engineering , computer science , biochemistry , programming language
Polyimides were prepared from diamines: 2,4,6‐trimethyl‐1,3‐phenylenediamine (3MPDA) and 2,3,4,5‐tetramethyl‐1,4‐phenylenediamine (4MPDA). 1,4‐Bis(3,4‐dicarboxyphenoxy)benzene dianhydride (HQDPA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), 3,3′‐4,4′‐diphenylsulphone tetracarboxylic dianhydride (SO 2 PDA), 3,3′,4,4′‐diphenylsulphide tetracarboxylic dianhydride (SPDA), pyromellitic dianhydride (PMDA), and 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoroisopropane dianhydride (6FDA) were used as dianhydride. The gas permeabilities of H 2 , O 2 and N 2 through the polyimides were measured at temperatures from 30 °C to 90 °C. The results show that as methyl and trifluoromethyl substitution groups densities increase from 7.73 × 10 −3 mol cm −3 to 13.50 × 10 −3 mol cm −3 , the peameability of H 2 increases 10‐fold at 60% loss of permselectivity of H 2 /N 2 ; however, the permeability of O 2 increases 20‐fold at 20% loss of permselectivity of O 2 /N 2 . For O 2 /N 2 separation, PMDA‐3MPDA has similar performance to 6FDA‐3MPDA and 6FDA‐4MPDA; all have higher permeabilities for O 2 than normal polyimides, and the P(O 2 )/α(O 2 /N 2 ) trade‐off relationships lie on the upper bound line for polymers. © 1999 Society of Chemical Industry