ABSTRACT
The solubility of the permeant in a polymer is defined as that volume (or mass) which dissolves in unit volume of the material under applied unit pressure. It is described by Henry's law,
The diffusion process is described by Fick's first and second laws. Fick's first law relates the flux to the concentration gradient:
ac 111 = -D-(2) ax
Where 111 is the permeant flux, i.e., the rate of flow per unit area, D is the diffusion coefficient or diffusivity, and acjax is the concentration gradient.
