What causes a crease in paper to stay that way?

I could have thought of a boring-er question but I think this suffices for now.

I was playing with a medical-type of wrist band from a party* and noticed that when I folded it, it stuck. I wondered what was happening down there on the molecular level. Was it a magnetic attraction or adhesion caused by particles being smashed together, like digging a trench in a field and having two large piles of dirt on either side of the trench, preventing the land from laying flat again(if you can picture the metaphor, basically a displacement of matter).

Does anyone know what is happening there?

*If you were wondering, “No, I was completely sober at the party.” :smiley:

For plastic you are actually causing the long chains of polymers to slide to new ‘streached out’ positions. As for paper - My guess is something simlular.

JELL-O :smiley: