I refer to rubber bands and other elastic materials.
In: Engineering
>I refer to rubber bands and other elastic materials.
Consider a box of uncooked spaghetti. The individual dried noodles themselves can flex a little bit, but in general are pretty rigid.
Now consider how they behave when cooked. They form a tangle that can stretch and deform but clump together if you pull too much. Also note that the length of thin noodles like spaghetti or ramen influences their tendency to get tangled and clump together when you try to eat them with a fork.
Likewise molecules of *Elastomers* like rubber have a long, randomly coiled, tangled, springy structure like cooked ramen.
In contrast hard plastics like nylon or polyethylene have long, straight molecules that are arranged all in rows like dried spaghetti in a box.
Further evidence of this kind of tangled structure can be seen in rubber balloons filled with helium. Helium atoms are very small and chemically inert. Because of this they can slowly diffuse through the gaps and holes between individual tangled rubber molecules and escape into the air, likewise air molecules can slowly diffuse inwards. The latter may be confusing but is largely driven by the fact that there’s a low concentration of nitrogen inside the balloon, rather than the small difference in pressure. This explains why rubber helium balloons will shrink and lose buoyancy as the helium slowly diffuses out through the thin rubber.
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