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Diffusion of Ethanol through EPDM
Posted by Robert Berger on October 31, 2006 at 20:49:24:
Hi,
I have an aerosol application where EPDM (Ethylene propylene diene monomer) polmyer is being used as a seal. The contents consist of a propellant (HFA-227) and Ethanol. We have conducted some experiements and the container appears to be losing ethanol at a much faster rate than the propellant. Elevated temperature accelerates the loss. The two contents are not coming out at proportional rates. The ethanol is coming out at ~10x rate.
The molecular weight of ethanol is smaller than the propellent (46 vs. 170)but its boiling point is higher and its partial pressure and concentration (almost 100x more propellant) in the container are lower. Does this sound like ethanol is diffusing through the Ethylene propylene diene monomer EPDM or does another mechanism explain what I am seeing? Please explain fugacity-chemical potentials of ethanol, propellant also
Thank you,
Robert Berger
Re: Diffusion of Ethanol through EPDM diffusion polymers 31/10/2006 (0)