WEBVTT - Why Do Balloons Stick To Our Hair?

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<v Speaker 1>Welcome to brain Stuff from how Stuff Works. Hey, brain

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<v Speaker 1>stuff is Christian Saker here. When you were a kid,

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<v Speaker 1>did you ever rub a balloon really fast against your

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<v Speaker 1>hair to make it stick? What about as an adult? Well,

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<v Speaker 1>after many years of speculation, Case Western Reserve University scientists

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<v Speaker 1>have pinpointed exactly why this party trick happens. We've known

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<v Speaker 1>forever that when two objects are rubbed against each other,

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<v Speaker 1>there's a build up of an electrical charge called static

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<v Speaker 1>electricity or tribo electric charging. If the two objects have

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<v Speaker 1>opposite charges, positive and negative, they'll stick together. But some

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<v Speaker 1>objects appear to charge more or stick more closely together

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<v Speaker 1>than others, like the balloon on your hair. Now, why

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<v Speaker 1>is that? According to a new study published in the

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<v Speaker 1>journal Physical Review Materials, the crux of the phenomenon lies

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<v Speaker 1>and how strained the balloon material is. For the purpose

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<v Speaker 1>of this study, the scientists stretched a film of polytetrafluoro ethylene.

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<v Speaker 1>Let's just call it PTFE for now. That's one of

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<v Speaker 1>the brand names for teflon. They took that and they

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<v Speaker 1>rubbed it against a film of unstrained, unstretched ptf E,

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<v Speaker 1>and they found that even though the materials were chemically identical.

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<v Speaker 1>They generated charge transfer in one direction as if they

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<v Speaker 1>had two different chemical compositions. The stretched or strange sheet

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<v Speaker 1>carried the positive charge, while the unstrained sheet carried a

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<v Speaker 1>negative charge. The more strained the material was, the more

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<v Speaker 1>likely it was to experience systematic charge transfer. This is

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<v Speaker 1>because the micro structure of the material was altered when strained,

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<v Speaker 1>leading to tiny holes and cracks. These imperfections allowed the

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<v Speaker 1>rubbing induced friction to facilitate charge transfer, leading to static electricity.

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<v Speaker 1>In a pre US release, co authored Dan Lax explained

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<v Speaker 1>that they think the void regions in the fibrils these

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<v Speaker 1>are tiny cell fibers. They think that those were strained

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<v Speaker 1>when the polymer had different bonding and thus a charge

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<v Speaker 1>that was different. The researchers also examined the phenomenon using

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<v Speaker 1>packing peanuts, which just love to stick to people's arms.

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<v Speaker 1>In fact, polystyrene peanuts and plastic bags are currently being

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<v Speaker 1>closely examined to give us a better understanding of static electricity. Ideally,

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<v Speaker 1>scientists will nail it down so precisely that they will

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<v Speaker 1>be able to control it, helping to prevent tribe electric explosions,

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<v Speaker 1>such as explosions of coal dust in minds and develop

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<v Speaker 1>more effective products, for example, pesticides that will stick better

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<v Speaker 1>to plants or paints that will stick better to cars.

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<v Speaker 1>It may not seem that dangerous, but in fact static

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<v Speaker 1>electricity can ignite fuel vapors at the gas pump, causing fire.

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<v Speaker 1>To avoid such a catastropheure try not to get back

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<v Speaker 1>in the car after you start the fueling process, because

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<v Speaker 1>sliding across the seat generates static electricity. If you must

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<v Speaker 1>re enter your vehicle, be sure to ground yourself first

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<v Speaker 1>when you get back out by touching the metal part

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<v Speaker 1>of your car door. Today's episode was written by Aliya Hoyt,

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<v Speaker 1>produced by Tristan McNeil, and For more on this and

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<v Speaker 1>other topics, please visit us at how stuff works dot com.