Units of gas permeability constants



Gas permeability constants of polymers are generally expressed by composite units which contain

equation image

Numerous combinations of various units to express each component units are used. However, permeability constants of nongaseous substances in polymer membranes are generally expressed by the units of cm2/sec, which are identical to the units of the diffusion constant. The relationship between constants in units of cm2/sec and conventional composite units for gas permeability constants is presented, and the advantage of using the units in cm2/sec to express gas permeability constants is discussed.