Saturday, January 14, 2012

Rubber based air condition?

Further tests are getting more and more interesting.

I took a rubber band (untapered) and stretched the middle part out, then waited until it had cooled down.

Then I relaxed it.

It was COLDER than the room temperature! The first pic shows the retracted band between my hands, the second one the whole band (with the ends beeing warmed from my hands).

This means that you can - in theory - build a fridge (or an air condition) with rubber. Take a slingshot outside, draw it out, wait about 20 seconds, then go with the stretched band back into the house, and let go.

You can build a "Sterling cooler" with this, except that a Sterling normally uses gas and not rubber...


  1. How very odd! I would have thought that either stretching or rebounding would have produced heat due to internal friction caused by molecular movement. This throws an entirely different slant to what occurs.

  2. In fact, rubber behaves like gas. When you compress gas, it heats up. When you release it, it cools down. Have you ever shot a co2 pellet gun? Then you probably noticed that the cartridge gets very cold after several quick shots, and at the same time the shots are getting weaker. Stretched out rubber works just like compressed gas.

  3. Yeah but you would have to find a way to take away the heat of the rubber after streaching, befor it can heat up the thing you want to cool. So if you solve this issue u may be able to cool down something with rubber.

  4. The easiest way is to wait ten seconds. The air cools the bands pretty quickly. Of course you can press the stretched bands against a heat sink made from a bit of copper tubing or so, that would be even quicker.

  5. Would this explain why slingshot bands perform poorly in cold weather?

  6. I think that has more to do with the fact, that cold makes rubber less streacheble and stiffer

  7. No, it is a phenomen called "Entropy" that causes this

    Check this article out:

  8. I have been about thermal energy and elastic energy in and I think the experiment you videotaped was interesting, it showed how with most elastic energy, more thermal energy is present.