Everyone knows the standard static electricity experiment. You grab yourself a perspex rod and a wool cloth and, after some vigorous rubbing (often with a few innuendos thrown in), suddenly your perspex has the ability to attract pieces of paper. Most people will also understand the mechanism of action, the transference of charge that leaves the rod negatively charged and the cloth positively charged. What most people won’t know however is that friction isn’t required to generate a static charge. This is what can lead to hilarious situations like the one in the video below:
So if friction isn’t a requirement for generating a static charge how do these address labels get it? The answer is actually pretty interesting and has to do with the way adhesives work. For these address labels the adhesion comes from a chemical reaction, meaning that the address labels had a form of bond with the backing before they were torn apart. When this bond is broken both materials will gain or lose electrons, depending on where the material sits on the triboelectric series. I’d hazard a guess that the material that the address labels is made up of tends more towards the negative end of the spectrum, meaning that bin holds a strong negative charge.
This is what is responsible for the labels floating around in a seemingly random fashion before ejecting themselves out onto the floor. The effect wouldn’t have been immediate, each label would only carry a small negative charge, however past a certain point the negative field would have become big enough to repulse the small weight of each of the labels. If they were so inclined they could throw a positively charged piece of plastic in there and they’d all be attracted which would also be pretty interesting.
Or, if you wanted some real fun, if they rubbed their head with a balloon and then dunked themselves in there all the labels would gleefully stick to them. Not that that proves much, just that it’d be hilarious to see someone with shipping label backing stuck to them.