PVC fumes when heated

PVC products like new shower curtains are known to emit toxic fumes, but is heat - say, 120 Celsius - likely to neutralize the fumes, or change them into something even worse?
(I mean the fumes alone, not the PVC; imagine taking a bottle of fumes and putting them in a dryer machine or heater.)

I don’t know about that, but I read somewhere that a new shower curtain outgasses something like 400 different noxious chemical fumes.

I doubt 120C would do anything except maybe intensify the odor. There is still some controversy about whether the plasticizers (typically phthalates) are seriously harmful in the amounts found in consumer products, and if so to what extent. I’m not aware of anything a consumer could do to make dangerous fumes safe - if there were such a process, the manufacturer would probably be doing it towards the end of the manufacturing process.

Now if you get hotter to the point where it burns, one of the decomposition products of certain plastics is dioxin.

I agree but If you’re thinking you can wash out all the fumes or evaporate them in a dryer that’s a bad idea. You’ll just lose the desirable plasticizers and degrade the material.

FYI, there are plastics manufacturers that specialize in PVC because the molten plastic releases corrosive gases (chlorine?) and typically PVC molds are stainless steel. The shops have lots of ventilation for workers and to help the equipment last longer. PVC molding presses are sometimes considered “sacrificial machines”.

That reminds me of an anecdote told to me by my polymer science professor about the first PVC raincoats in the 1950s. They were trialled in New York and became quite the thing as they were so ‘modern’ looking. Then came the New York winter and there were reports of them getting so brittle in the cold they literally shattered on the wearer as they sat down on the subway. The manufacturers responded by adding plasticizers to help retain their flexibility. Then came the New York summer… Reports started to come in of raincoats melting off their coat hooks during a heatwave, ending up as a puddle on the floor below. Hopefully on the third iteration the manufacturers subjected the garments to some proper environmental testing.