Force Required to Peel Tape: Exploring Energy & Adhesive Forces

[jangheej]

I have a question about force needed to peel a tape.

1. If an external force does work on a tape, to what kind of energy is it transformed?
There must be some kind of energy stored in the tape, but I can't think of any.
some papers mention "strain energy", but I don't grasp the concept of it.

2. Where does the adhesive force come from? Is it from Van der waals force?

3. I drew the forces in the attached file, and accordingly, since the vertical component of the external force increases as the theta increases, it must be easier to peel the tape off the surface when the angle increases. But theories and simple experiments show the opposite result. What is wrong with the picture?

 

[soothsayer]

I may be going a bit out on a limb here, but

1) I imagine there could be small amounts of heat energy released by destroying adhesive bonds

2) It depends on the type of adhesion, for chemical/electrostatic adhesion, I don't think it would be, but I think Van der Waals forces play a small role any time there is an adhesive force between two objects. For something like tape, this role is small compared to the chemical adhesive.

3) I just think the system is a bit more complex that that, I would suggest looking at the point where the tape where the peeling is occurring between the tape and the surface. The angle between the peeled tape and tape stuck to the surface is not perfectly sharp, but rounded. That could have something to do with it.

Hope that helped.

 

[Andy Resnick]

I have a question about force needed to peel a tape.

Peeling tape off a surface is a surprisingly enormously complicated problem. First, adhesion is not that well understood.

http://en.wikipedia.org/wiki/Adhesion

Van der Waals forces are often put forward as an explanation, but that's only because Van der Waals forces are a blanket term to describe all intermolecular forces other than electrostatic/electromagnetic ones- that is, it's a catch-all term for 'we don't know the details'.

Here's a simple trick you can do that will thoroughly confuse you-

loosely lay a piece of tape onto a flat surface. A short distance from one end, use your fingernail to press a thin stripe of tape into contact with the surface, creating a line of compression. Then, carefully and slowly peel off the tape- you will see the compression line travel down the length of the tape, ahead of where the tape comes up. How does this happen?

N.A. de Bruyne, The action of adhesives, Scientific American 206 (1962), pp. 114–126

DR.NORMAN A. de BRUYNE "How Glue Sticks" Nature 180, 262-266 (10 August 1957) doi:10.1038/180262a0

 

[Dadface]

I have a question about force needed to peel a tape.

1. If an external force does work on a tape, to what kind of energy is it transformed?
There must be some kind of energy stored in the tape, but I can't think of any.
some papers mention "strain energy", but I don't grasp the concept of it.

2. Where does the adhesive force come from? Is it from Van der waals force?

3. I drew the forces in the attached file, and accordingly, since the vertical component of the external force increases as the theta increases, it must be easier to peel the tape off the surface when the angle increases. But theories and simple experiments show the opposite result. What is wrong with the picture?

Are you sure about your conclusion to number three?I suggest you try it out.
You may get some useful information by googling "triboluminescence".

 

[luthier]

Try this...
take a dry erase board and derive maxwells equations from first principles.
When done , take the dry erase eraser and erase the board. While still holding the eraser
touch something electricialy grounded. The spark you see represents the electrostatic
energy which was holding the ink onto the board.
(If you try it without ink, no spark. )
Try it...
Tim