I need to get some rough calculations done on the permeability of
HFC-134a across various polymers (polyamide, polyethylene
terephthalate, etc) at different pressures and different wall
thicknesses of 0.25mm - 0.75mm. Ideally I would like an Excel
spreadsheet created that I could plug in different values.  I am
trying to determine if I can make a small injected molded part
containing HFC-134a (Chemical Name 1,1,1,2-tetrafluoroethane,
Molecular Formula CH2FCF3) under pressure. The part would be a tiny
doughnut shaped container with the gas at 80psi - 100psi. I need to
determine what mass of gas and how much pressure I would lose over a
two year period. Additionally, I would look for suggestions and
calculations on how to improve the permeability of the polymer with
coatings and/or unique blends. I can provide more detail.