GAS-TRANSPORT IN POLY[BIS(TRIFLUOROETHOXY)PHOSPHAZENE] ABOVE THE T(1) TRANSITION

Gas permeation measurements were performed by the time-lag method for 13 gases in poly[bis(trifluoroethoxy)phosphazene] above the mesophase transition, T(1) transition, of the crystals. Hysteresis was found in the temperature dependence of the permeability coefficients for CO2, O2, and N2 in the transition region as observed by dilatometry and differential scanning calorimetry. Independently the solubility of CO2 was determined gravimetrically above and below T(1). Noticeable change and hysteresis were also observed in the temperature dependence of the solubility coefficients. Diffusion of CO2 in the mesophase is suggested from the permeation and sorption measurements. Gas transport parameters of CO2 in the mesophase are estimated, and the contributions of the mesophase and the crystalline phase to gas transport are considered.