|MadSci Network: Chemistry|
Robert: The "plastic" odor you are referring to may in fact be the residual odor of the polypropylene or PET resin which the container is made of. It could also be any of a number of mold release agents, anti-static agents, or even the antioxidants added to give the container the ability to resist degradation brought on by free radicals in the atmosphere and to protect the container if used to heat food in a microwave. A common mold release (and anti-stat) that is used is erucamide. Calcium stearate may be used as a processing agent and acid scavenger to remove any residual catalyst from the synthesis of the PP or PET. Any or all of these types of additives are more likely to be the 'odor' causing species rather than the PP or PET due to their size difference. The plastic(PP or PET is a much larger molecule than any additive and therefore is very stable and not likely to break down easily. These additives work because they are so small compared to the resin they are in that they migrate to the surface and impart the desired characteristic of that additive to the whole part. I hope this helps you in your quest.
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