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Cool balloons

Saturday 21 March: 10:00am - 12:45pm

Department of Materials Science and Metallurgy, Goldsmiths 2, 27 Charles Babbage Road, CB3 0FS

What happens when you stretch a balloon very fast? An ordinary party balloon is made of rubber. In its normal state, a balloon consists of a network of disordered polymer chains, which somewhat resembles a plate of spaghetti. On stretching the balloon, the polymer chains align in the direction of the applied force, increasing the degree of internal ordering of the chains. If the stretching is done very fast, this change in internal structure leads to an increase in temperature that can be easily detected using your lips, or in a more sophisticated manner using an infra-red camera. On releasing the balloon after it has recovered its initial temperature, the balloon gets cold, and can be used for cooling another object. This is a perfect illustration of caloric materials, which could be the key to new environmentally friendly refrigeration technologies.

Observe these changes of temperature with researchers, and an infra-red camera, from the Department of Materials Science and Metallurgy.

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Age: All ages, Hands-on, Drop in, Free