关键词:

6FDA聚酰亚胺, 巨正则Monte Carlo, 溶解系数, 自由体积

Abstract:

Molecular simulation was used to model the d-spacing and fractional free volume of 6FDA-durene，6FDA-pPDA and their copolymer 6FDA-durene/pPDA. Calculation results were in agreement with experimental data. Grand canonical Monte Carlo (GCMC) calculations were performed to simulate the sorption of O₂, N₂, CH₄ and CO₂ in the polyimide. The simulation results indicated that the COMPASS force field was suitable to describe the sorption of O₂, N₂ and CH₄. The calculated solubility coefficients of O₂ ,N₂ and CH₄ were in agreement with experiments. But the solubility coefficient of CO₂ exhibited high deviation (about 50%) from the literature value. The main reasons might be: (1) swelling effect of CO₂ was not considered in the simulation process; (2) COMPASS force field could not describe the interaction of CO₂ and —CF₃ of the 6FDA-polyimides. The calculated solubility coefficients decreased in the sequence of the inherent condensabilities of the gases, namely, CO₂, CH₄, O₂ and N₂. The solubility coefficients in different polyimide increased with increasing fractional free volume. The 6FDA-polyimides showed better solubility selectivity for CO₂/CH₄ than O₂/N₂. Copolymerization could not improve the solubility selectivity remarkably.

Key words:

6FDA聚酰亚胺, 巨正则Monte Carlo, 溶解系数, 自由体积