Influence of temperature on gas solubility in thermally rearranged (TR) polymers

Abstract

Thermally rearranged (TR) polymers have been the subject of many fundamental studies, but the effect of TR conversion on temperature-dependent transport properties is largely unexplored. Sorption isotherms for N 2 , CH 4 , and CO 2 in HAB-6FDA polyimide and its TR analogs were measured at temperatures ranging from-10 °C to 50 °C and pressures up to 27 atm. Solubilities increase with decreasing temperature for each gas and sample tested. At low TR conversions, the sorption process initially becomes less exothermic. However, enthalpies of sorption do not significantly change with TR conversion after the initial stages of rearrangement. Enthalpies of sorption in TR polymers are qualitatively similar to those of other high free volume materials. Solubility selectivity for CO 2 /CH 4 at 10 atm did not change with temperature due to similar enthalpies of sorption for CO 2 and CH 4. Sorption data were fit to the dual mode model at different temperatures, and model parameters were correlated with polymer and penetrant properties.

Elucidation on the Effect of Operating Temperature to the Transport Properties of Polymeric Membrane Using Molecular Simulation Tool

“…In addition, solubility is reported to tally with the Arrhenius calculation with respect to operating temperature based on previous published literatures [12,23], such as that demonstrated (6).…”

“…Gameda et al elucidated the mixed gas sorption of CO 2 /CH 4 in polymer of intrinsic microporosity (PIM-1) in between 25 and 50°C [11]. Stevens et al reported the decrement in gas solubilities with increment in temperature at varying thermally rearranged (TR) polymeric membranes [12].…”

Nonequilibrium Lattice Fluid Modeling of Gas Solubility in HAB-6FDA Polyimide and Its Thermally Rearranged Analogues

“…2 was used to simultaneously fit, for each polymer, experimental infinite dilution solubility coefficients for different light gases, i.e. H2, He, N2, CH4 and CO2, at multiple temperatures, ranging from -10 to 50°C 25,26,27 . In this procedure, the polymer characteristic lattice fluid parameters, T*, p* and *, were treated as fitting parameters and adjusted to the experimental sorption data, while the polymer-penetrant interaction parameter, 12 k , was set equal to zero 12 .…”

“…In Fig. 2 Nitrogen sorption isotherms in HAB-6FDA at multiple temperatures 27 are presented in Fig. 2-B.…”

“…Three TR samples were considered, which were obtained by treating the polyimide precursor at different temperatures for a prescribed time 6,7,27 . The extent of thermal rearrangement increases in the following order: TR350-1h < TR400-1h < TR450-30min (cf., Table 2).…”