When you melt styrofoam what happens to the mulicules that makes it condence and harden ?

Question

What exactly happens to the mulicules that make the styrofoam condence and harden when it is melted ?

Answer 1

Styrofoam is actually the plastic material polystyrene which contains a lot of trapped gas to make it into a solid foam material.

The trapped gas may be air or carbon dioxide.

When melted, the gas is free to bubble out and the foam
"collapses". Without the gas present, the polystyrene molecules are much closed together, which makes the material denser (heavier) and much harder which it cools and solidifies.

Answer 2

they're dissolved in solution and reacted to make something else