Stretching a rubber band makes it hot. Releasing the stretched ... check out [Al Williams] recent article about building a DIY heat pipe.

Students stretch pre-cut rubber bands to their lips, stretch the rubber bands, and then allow them to contract. The rubber bands grow warmer as they expand and cool as they contract. To Conduct ...

As the rubber bands are heated up by the heat gun, the polymers making up the rubber band experience an increase in entropy. This causes the rubber band to contract and shorten. As a result, the ...