Why Do Balloons Stick To Our Hair?

It's a hair-raising experience. BrainStuff explains the secrets of static electricity.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works. Hey, brain
stuff is Christian Saker here. When you were a kid,
did you ever rub a balloon really fast against your
hair to make it stick? What about as an adult? Well,
after many years of speculation, Case Western Reserve University scientists
have pinpointed exactly why this party trick happens. We've known

(00:26):
forever that when two objects are rubbed against each other,
there's a build up of an electrical charge called static
electricity or tribo electric charging. If the two objects have
opposite charges, positive and negative, they'll stick together. But some
objects appear to charge more or stick more closely together

(00:47):
than others, like the balloon on your hair. Now, why
is that? According to a new study published in the
journal Physical Review Materials, the crux of the phenomenon lies
and how strained the balloon material is. For the purpose
of this study, the scientists stretched a film of polytetrafluoro ethylene.

(01:07):
Let's just call it PTFE for now. That's one of
the brand names for teflon. They took that and they
rubbed it against a film of unstrained, unstretched ptf E,
and they found that even though the materials were chemically identical.
They generated charge transfer in one direction as if they
had two different chemical compositions. The stretched or strange sheet

(01:31):
carried the positive charge, while the unstrained sheet carried a
negative charge. The more strained the material was, the more
likely it was to experience systematic charge transfer. This is
because the micro structure of the material was altered when strained,
leading to tiny holes and cracks. These imperfections allowed the

(01:52):
rubbing induced friction to facilitate charge transfer, leading to static electricity.
In a pre US release, co authored Dan Lax explained
that they think the void regions in the fibrils these
are tiny cell fibers. They think that those were strained
when the polymer had different bonding and thus a charge

(02:14):
that was different. The researchers also examined the phenomenon using
packing peanuts, which just love to stick to people's arms.
In fact, polystyrene peanuts and plastic bags are currently being
closely examined to give us a better understanding of static electricity. Ideally,
scientists will nail it down so precisely that they will
be able to control it, helping to prevent tribe electric explosions,

(02:38):
such as explosions of coal dust in minds and develop
more effective products, for example, pesticides that will stick better
to plants or paints that will stick better to cars.
It may not seem that dangerous, but in fact static
electricity can ignite fuel vapors at the gas pump, causing fire.
To avoid such a catastropheure try not to get back

(03:02):
in the car after you start the fueling process, because
sliding across the seat generates static electricity. If you must
re enter your vehicle, be sure to ground yourself first
when you get back out by touching the metal part
of your car door. Today's episode was written by Aliya Hoyt,

(03:26):
produced by Tristan McNeil, and For more on this and
other topics, please visit us at how stuff works dot com.