Heat at which shampoo will turn into something else

[Velocity]

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?

[si_blakely]

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.

[Lightray]

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.

[lazybratsche]

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.

[Lightray]

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

[lazybratsche]

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

The thermal decomposition of 31 shampoos was investigated. The decomposition of these formulations has been found to proceed in three stages. In the temperature range from 303 K to 443–463 K, a mass loss of 72 to 93% occurred, which is connected with the release of liquid components of the shampoos. In the second and third stages, a mass loss of ca. 12% is observed, which is associated with the decomposition of the remaining components of the formulation. The residue after the decomposition of shampoos is a mixture of inorganic compounds.