Hardened polyurethane remover I've looked at the MSDS of a couple of products for removing hardened polyurethane (PU) foam. Both contained only ethanolamine as a dangerous substance, but only between 1-5%. So I'm guessing this might not be the active substance. The Wikipedia page on polyurethane doesn't indicate any degraders (and the page on polymer degradation doesn't mention polyurethane), so what (active) substances are typically used to degrade hardened polyurethane in commercial cleaners?

I also found that some metal acetate-ethanolamine complexes can be used as catalysts for preparing PU foam. So possibly ethanolamine is the active substance or just a catalyst for removal as well. Can someone shed some light on the purpose of ethanolamine?



Example for one of the products I was looking at "Soudal PU remover SDS"; there's also a consumer leaflet for that one which might have additional hints. It's "very active", "odourless", "free of aromatic hydrocarbons", pH 10.5.
The one solvent I see referenced the most for polyurethane foams is N-methyl-2-pyrrolidone or as the the cool kids call it: NMP. You don't have to just take my word for it a certain supplier that I have no affiliation with sells it for this purpose: Spray Foam Systems NMP.

As far as the purpose of ethanolamine, it must either be reacting to reduce chain length.  If you look at the urethane group below the Carbon bonded to two oxygens and a nitrogen is susceptible to attack by the basic ethanolamine. This reaction would break the molecular bonds making the polymer chains shorter and thus more mobile and more easily dissolved, thus saving time. This explination is a little hand-wavy but I didn't want to go deep into organic reaction mechanisms.