Gas diffusion through PET bottles

For figures and more on carbon dioxide diffusion in PET, please go to the gas diffusion section or visit the support / migration support page.

Posted by Nicolas Aubry on February 14, 2005 at 23:00:42:

Im studying the diffusion of carbon dioxide and oxygen through a PET bottle. Ive seen a figure showing a high rate of carbon dioxide rate just after filling the bottle at 25°C which decreases and becomes linear after 20 days. Im thinking about sorption of CO2 into microvoids to explain this phenomenon, can somebody help me or suggest me another solution ? As well, do you have an explaination to explain the permeation rate of carbon dioxide between a small and a large bottle of PET ? Ive heard of several mechanims, do you have any idea ?
Thank you

Posted by Nicolas Aubry on February 14, 2005 at 23:08:47:

Ive been surprised when Ive seen that in PET the permeation of carbondioxide is much higher than that of oxygen. This is despite the fact that the oxygen molecule is smaller than carbon dioxide. What is the reason for this? Diffusivity ? But I have some values and this is not corresponding to a good explaination. What about permeability and chemical degradation of the polyethylene terphthalate?
Thanks