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When you buy plastic sheets such as acrylics, polycarbonate sheets etc, they come with a paper/plastic protective film. Like in this image :

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Protective Film for Acrylic Sheet PMMA Panel

You notice that there is no adhesive (at least not something tacky) that is present on the sheets, and there is no residue when the sheet is peeled off, I was wondering if anyone can shed some light on how these protective films are applied ?

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  • $\begingroup$ Michael from vsauce makes this exact same question to Adam Savage (of Mythbusters fame) in this video, but got no answer. Also, that whole video is awesome. $\endgroup$ – Wasabi Jan 30 '17 at 0:01
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The material is called "Electrostatic Protective Film".

It is manufactured by letting the plastic film cool in a strong electrostatic field: there are high-voltage electrodes on top and bottom of the plastic. This causes the polar molecules in the plastic to align so that one side of the film has a positive charge and the other side has a negative one.

This charge will persist quite long, and will keep the film adhered to the plastic sheet by electrostatic forces. However, because the electrostatic force is quickly reduced by distance, it is important that no dust gets between the protective film and the base plastic during manufacturing.

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  • $\begingroup$ I think it's worth noting that the double-sheet is pretty clever in what it does. You say " it is important that no dust gets between the protective film and the base plastic during manufacturing" which is mutually beneficial for the plastic film and what it protects. That way you know the surface is very clean with a good finish. $\endgroup$ – JMac Jan 30 '17 at 11:47
  • $\begingroup$ Thanks for the answer ! Can this also happen with other materials such as glass ? $\endgroup$ – cpv Jan 31 '17 at 8:31
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    $\begingroup$ @cpv My knowledge here is a bit limited, but I'd assume the protective film can cling to most surfaces. I think I've seen it used even on metal surfaces. But as for manufacturing electrostatically polarized glass, that is probably not possible as it doesn't have polar molecules in its chemistry. $\endgroup$ – jpa Jan 31 '17 at 8:49
  • $\begingroup$ There are adhesives that are not electrostatic in nature that will stick to their substrate well but other things poorly sort of like a Post-It note and these are also sometimes used for sticking the plastic and glass screen protectors onto cellphones, they leave no residue on smooth surfaces. I expect for a disposable protective sheet they would usually be more expensive than desired though the protective plastic on metal stock is often held with a contact adhesive sort of thing. $\endgroup$ – KalleMP Feb 2 '17 at 8:26

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