Dr. Steven Mann

With paper, you've got these individual fibres, and if you look at the structure, they're made from cellulose.

And cellulose is just a long chain of glucose molecules.

We all know glucose, it's just a common everyday sugar.

And glucose contains a particular chemical group called the hydroxyl group, an OH group.

And OH groups actually act like little magnets.

That's right.

On the OH group, the oxygen is negative, the hydrogen is positive.

And if you've got two different fibres now, each with an OH group, then the oxygen on one fibre will be attracted to the hydrogen on the other fibre.

Yes.

And the hydrogen on that will be attracted to the oxygen.

And that's a phenomenon that we call hydrogen bonding.

And without hydrogen bonding, we'd all be lumps of jelly on the floor.

You wouldn't have a sheet of paper.

Nature makes the OH groups when it makes the glucose molecules.

And the paper maker gets the OH groups on one fibre as close as he can to the OH groups on another fibre so that the bonding can happen.

If you think about the sheets of paper, you've got the fibres themselves and you've got the fibre-fibre bonding.

If you put a crease in the paper, what you're actually doing is you are destroying some of those hydrogen bonds and they've gone forever and you can never undo that damage.

And the other thing you do is you damage the fibres.

Some fibres you will break, some fibres you will partly break, and some fibres you won't break.

So for that reason, once you've creased a piece of paper, you can't really uncrease it.