|MadSci Network: Chemistry|
Sorry for the delayed answer. It took some time to find it. I may not even have the correct one. But it looks like the breakdown of PVC in the presence of fats and oils is due to the leaching out of the plasticizers inside PVC that have been added to it to improve its processability or flexibility. When in contact with oils (not mineral oils - PVC are extremely in mineral oils) especially cooking oils and fats, the plasticizers may be drawn out from the PVC resulting in breakdown of the PVC soles. SOmetimes polymeric plasticizers are added to PVC to make them oil-resistant. Applications such as geomembranes use such oil-resistant plasticizers. I also posted this question in sci.polymers and I quote below a part of the response. "We went on to test the PVC in the presence of a number of other systems that were not hydrocarbon in nature, including synthetic esters, and vegetable oils of a variety of types, and we found that the same effect was occurring. It did appear that the oils were leaching out the plasticisers, an effect later confirmed using quantitative FTIR (infrared spectroscopy). As yet, we have not found any oil that does not have this effect with PVC." So there goes your answer. Have fun
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