Why Inflating Balloons Causes them to Gain a Positive Charge

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tony873004
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Two new uninflated balloons do not attract or repel each other. But after blowing them up, they repel each other and stick to the wall, without having to be rubbed against hair or anything else. Why do balloons gain charge simply by being inflated?

It seems that the newly-inflated balloons gain a positive charge, as they attract other balloons that have been rubbed against hair. Does inflating a balloon cause it to lose electrons?
 
on Phys.org
Clearly the balloons you have inflated have gained a net positive charge.
Does the effect occur when you inflate the balloons with bottled gas?
Does it still occur in cold weather?

Does touching something to it reduce the positive charge?
 
I didn't know you could charge a balloon by inflating it
 
I didn't know that either. My experience told me I had to rub it against my hair. Everything I read and everything I googled said the same thing. It only happens with one particular brand of balloons which are designed to be water balloons. The larger party balloons don't acquire charge when inflated.

I haven't tried bottled gas, or cold weather. The charge does get reduced when you handle the balloons, and it eventually wears off. Two balloons hanging from strings repel each other for a few hours, slowly coming closer until they touch several hours later.
 
I have a vague recollection of the effect you are talking about.
It could be that handling the balloon as you inflate it is what is doing the trick - though I'd expect that to provide the opposite charge.

Sunlight (or room lighting) could be knocking electrons off the surface, particularly if it is warm (which will happen in rapid inflation of thin balloons) - something that will be material-dependent.
You could try modestly inflating a balloon - discharging it - then seeing if you can get it to take a positive charge by exposure to bright sunlight or rapid heating or motion of warm air (hair-blower).
 
That's a strange phenomenon. Are you sure you are inflating the water balloons and the party balloons with the same method? The same pump?
Also does the charging only happen the first time you inflate them? Will they charge again when you deflate and then inflate them a second time?