As temperatures fire up for summer, you might be looking for new ways to cool off. Why not use rubber bands?
The Applied Science YouTube video uses a fun property of stretching and relaxing rubber bands to chill out a little. Playing with a rubber band, you might notice that it heats up as it stretches and cools a bit as it relaxes. The video even demonstrates this using a thermal imaging camera. It's easy to write this off as heat from friction, but something more fundamental to rubber and thermodynamics is at play.
As a rubber band is stretched out, the molecules become more ordered, and warm up in a similar way to how compressing a gas causes it to heat up. Releasing the rubber band bounces it back toward a more tangled-up state, and it cools down. Under the thermal camera, the change is distinct.
But just understanding the concept isn't enough, and the video moves on toward the question of whether a refrigerator could be constructed using rubber bands as a cooling mechanism. They rout a box, a wheel (based on a rubber band bicycle wheel concept, using heat to spin a wheel with rubber band spokes), and some fans, and get set to construction.
The sealing admittedly isn't great, and there are some other possible problems with the design, but it solidly looks like an impressive ice box, just without any ice. The rubber bands are stretched on a wheel so they can release heat as they stretch on the outside of the box and produce chill on the inside of the box, turned by a crank outside the box.
The results are mixed, with all the variables causing some statistical white noise, but he comes away with a conclusion that the inside of the box is at least a couple degrees cooler than outside. It won't be keeping any popsicles frozen, but that's all the better reason to eat them quickly.
Kyle Brown is a reporter for Rubber & Plastics News who watched a lot of Mr. Wizard and Bill Nye while growing up. Follow him on Twitter at @kbrownRPN.