Heat at which shampoo will turn into something else

Let’s say you take Head & Shoulders shampoo - which is somewhat oily - and put it under the direct hot blast of a hair dryer inches away. Would it turn into a different chemical?

Probably not. But conditioners and oily shampoos are emulsified, and excessive heat will probably cause it to “split” into a soapy water fraction and an oily fraction.

The decomposition temperature of a detergent is largely dependent on the chain length of the organic molecule. The abstract of this study suggests decomposition is occurring between 303K (~86F) and 443-463K. The lower end of that range seems more likely; even high-temperature detergents usually decompose well before 443K. So, it looks possible that a hairdryer could decompose shampoo.

I think you put in the wrong link. Good info though.

For one point of comparison, in the I routinely use SDS (aka sodium dodecyl sulfate, SLS, sodium lauryl sulfate), one of the common detergents in shampoo and a lot of other household products. I can boil it over and over again without functional degradation. That’d make it immune to a hairdryer, but not a proper heat gun.

There are lots of other detergents and compounds in shampoo, some volatile, some which probably decompose or react at lower temperatures than SDS.

Whups. Should be this on Thermal Decomposition of Shampoos (full study available for purchase).

Thanks. It sounds like any decomposition starting at 303 K is merely evaporation of water and other assorted volatiles: