Page 360 - Academic Press Encyclopedia of Physical Science and Technology 3rd Chemical Engineering

P1: GLQ Final Pages
Encyclopedia of Physical Science and Technology EN009K-419 July 19, 2001 20:57

Membranes, Synthetic, Applications 295

FIGURE 8 Literature data for CO 2 /CH 4 separation factor vs CO 2 permeability.

The factors affecting the selectivity and permeability of S. The diffusion coefficients of gases in glassy poly-
polymer membranes to different gases are best discussed mer membranes are strong functions of the penetrant gas
on the basis of Eqs. (12) and (14). As noted in Eq. (12), the concentration in the membranes (or of the gas pressure),
permeability coefficient, P, of a penetrant gas in a polymer and depend also on polymer morphology (crystallinity,
membrane is the product of a (concentration-averaged) orientation), crosslinking, and chain mobility. The chain
diffusion coefficient, D, and of a solubility coefficient, mobility depends, in turn, on the polymer free volume, the

FIGURE 9 Literature data for O 2 /N 4 separation factor vs O 2 permeability.