Thermoplastic Rubber

September 14, 2012, by Debra Lynn Dadd

Question from E.K

Hi Debra! I have been a big fan of your site, thank you so much for all your hard work! I was wondering if you had any information on Thermoplastic Rubber being used on slippers. I'm thinking of purchasing a pair but am finding anything solid online about this material. Thank you so much for your time! 

Debra's Answer

The term thermoplastic means that the material become pliable or moldable above a specific temperature and returns to a solid state when it cools. A stick of butter, for example, or an ice cube, is solid when cold and melts above a certain temperature. It can then be poured into a mold and formed into a new shape, and hold the shape when cooled, as long as it is not heated above the temperature than makes it melt.

The opposite of thermoplastic is thermoset, which means that the material will hold the shape regardless of the temperature. Plastic dice is an example of a thermoset.

Rubber is rubber, which can be made from the sap of the rubber tree, or from petroleum. Usually it is made from petroleum unless otherwise specified.  If you are sensitive to latex, make sure you verify if a rubber product contains natural rubber latex (NRL).

Thermoplastic rubber is more commonly called thermoplastic elastomer (TPE). This is a class of materials that have properties of both rubbers and thermoplastics.

The MSDS for one brand of thermoplastic rubber does not indicate any health problems from handling pellets of this material. It does warn of toxic fumes from melting down the pellets to put into molds to make various products. But in the formed state there is no warning.