Quote Originally Posted by Gerald C Koch View Post
Here are some oxygen permeability data from the following website http://www.ucc.ie/fcis/PKplastics.htm

The larger the value the greater the oxygen transfer rate.

LDPE 7900 > HDPE 2900 > PVC 120 > PET 95 (units cm3/m2.24h.atm)

The difference between the two polyethylenes and PET and PVC is striking.
I understand the theory, and I thank you for posting it. What it doesn't explain is why the accordion bottles still work fine.