Hello, this question is purely out of curiosity, please help to enlighten me.

Question

A hot water bag (one of those rubber ones with the rubber stopper at the top you screw in) was hidden under my bed for about a month. It was filled with a bit of water and folded in half during this period. Hidden the the middle, against the crease of the fold, were ear phones (or ear buds) with rubber encased wiring.

When I finally found it, after a month of lying in waiting, I unfolded it and found that the rubber on the wire was all flat, like it had melted and at the crease in the hot water bag there a hole was formed, like it's rubber had also melted. Water was leaking out now... The hole's rims did not look burned or crisp, it look like it had just thinned out and disappeared. The hole was exactly where the rubber wiring was touching the hot water bag.

Note: the water inside was lukewarm at the time it was put in the bag, not hot at all.
An other note: it is summer time, weather varying between 20-35 degrees Celsius.

All I wish to know is how this happened. Such a waste of a hot water bag and ear phones for my mp3 :(

Thank you for your time! I look forward to your explanations. :)

Answer 1

I will give an "illustration" as to how I found it.

============ll
ll ll========= ll
ll ll@
ll ll========= ll
============ll.

All the parallel lines illustrate the hot water bag and how it was folded. The "@" is to represent the earphones hidden in the crevice of the hot water bag. Hope that helps to give you an idea.

Answer 2

My best guess is that the "rubber" of the hot water bag and the "rubber" of the ear buds may not have been rubber but different kinds of plastic. At elevated temperatures different plastics will stick to each other and different rubbers will stick together. I have had that happen (not with water bottles and ear buds) but with other objects. I tried gluing a piece of plastic that had broken with some plastic glue and the glue dissolved the object I was trying to glue. There are so many additives these days that are put into plastics as well as different kinds of rubbers with additives that sticking together is not that uncommons. Actually, they just melt into each other.

Answer 3

Thanks Dr. Bob! :D You're the best!