Originally Posted by Brewskii
The real key to carbonation is CO2 pressure -and lots of it -too much for most plastic vessels.
Lots of plastic vessels are fine for carbonation. For example, about a billion soda bottles that are produced every day. Mr. Beer kits come with plastic bottles. Also, I have seen small party kegs which are plastic, I believe they are called a party pig? I'm guessing that's a brand name.
If the vessel was designed for carbonated liquids, it should be fine...to a point. The brewer needs to understand how much carbonation will come from a set amount of sugar. I hope he does, or he is headed for a sticky mess.