The permeability coefficient of a type of small gas molecule in a polymer is dependent on absolute temperature according to the following equation:

Whereand Qp are constants for a given gas-polymer pair. Consider the diffusion of water through a polystyrene sheet 30 mm thick. The water vapor pressures at the two faces are 20 kPa and 1 kPa, which are maintained constant. Compute the diffusion flux [in (cm3STP)/cm2-s]at 350 K? For this diffusion system,

PM0 = 9.0 × 10-5 (cm3 STP) (cm) / (cm2 -s-Pa
Qp = 42,300 J/mol
Assume a condition of steady-state diffusion?

Transcribed Image Text:

exp Рм Рм, ех р RT