Gas transport properties of 6FDA-durene/1,4-phenylenediamine (pPDA) copolyimides

Wen Hui Lin, Rohit H. Vora, Tai-Shung Chung

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230 Scopus citations


We have determined the gas transport properties of He, H2, O2, N2, and CO2 for 6FDA-durene homopolymer and 6FDA-durene/pPDA copolyimides. The 6FDA-durene exhibits the highest permeability with the lowest selectivity. Permeability of copolymers decreases with increasing 6FDA-pPDA content, while permselectivity increases with an increase in 6FDA-pPDA content. 6FDA-durene/pPDA (50/50) and 6FDA-durene/pPDA (20/80) materials have O2 and CO2 permeabilities greater than those calculated from the addition rule of the semilogarithmic equation. These higher deviations from the additional rule of the semilogarithmic equation are mainly attributed to the fact that these copolyimides have higher solubility coefficients than those calculated from the additive rule. The Tgs of 6FDA-durene/pPDA copolyimides decrease with an increase in 6FDA-pPDA content. Tgs predicted from the Fox equation are lower than the experimental data, and the their difference increases with an increase in pPDA content, implying the copolyimides of 6FDA-durene/pPDA may have greater interstitial space among chains because of the conformation difference, and thus create more fraction free volume compared with the ideal case of simple volume addition. Density measurements also suggest these two copolymers have greater free volumes and the fractions of free volume, which supporting the gas transport results. The thermal stability and β-relaxation temperature have also been studied for these copolymers.

Original languageEnglish (US)
Pages (from-to)2703-2713
Number of pages11
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number21
StatePublished - Nov 1 2000

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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