The apparent gas diffusion and solubility coefficients
of the UV-cured membranes as a function of UV irradiation time are presented in Fig.
The "time-lag" method of determining diffusion and solubility coefficients in semicrystalline polymers generally gives good agreement with results derived from static sorption measurements.
Figure 14a-c shows the permeability, diffusion, and solubility coefficients for various gases plotted versus birefringence for the as cast, once drawn (oriented), and twice drawn (ultra-oriented) films respectively.
Time-lag permeability measurements showed decreases in the permeability, diffusion and solubility coefficients with orientation.
The estimated errors in gas permeability, diffusion, and solubility coefficients are about 5-15% for He, [H.
The solubility coefficients of these gases, calculated as the ratios of permeability coefficients to the respective diffusion coefficients, are listed in Table 2.
In the following, the diffusion and solubility coefficients are discussed separately in order to clarify the influence of the molecular parameters.
Linear relationships have been found in our report (11) between the solubility coefficients of various gases in PANi and the boiling points of the gases or their critical temperatures.
m - 1) are ratios of the solubility coefficient of the neighboring layer, such as [varSigma.
1]), and one can determine, in turn, the thickness ratio from the point of the deviation if the diffusion and solubility coefficient ratio between the surface and inserted layer are already known.
m), are diffusion coefficients and solubility coefficients within the respective layers.
In fact, while in certain cases, researchers ascribed the low permeability values to surprisingly low solubility coefficients
(14-18), in one case the low value of permeability was attributed to a low diffusion coefficient (19).