What chemical melts plastic? --- James, Clinton, N.J.
Marshall Brain Answers:
It depends on the type of plastic you are trying to melt. For example, acetone melts styrofoam, as demonstrated in this video:
Styrofoam is made of polystyrene inflated with a lot of air. So acetone will melt anything made of polystyrene.
Another common plastic is polyurethane, which we see as polyurethane foam (in seat cushions for example) and polyurethane sheets (e.g. for drop cloths). If it is not cross-linked, something like methyl ethyl ketone would dissolve it.
PET (polyethylene terephthalate) is the plastic used in soda bottles. In the video above you can see that acetone has no effect on PET. This page describes a chemical process for breaking it down.
This page describes a process for breaking down fiberglass resin using denatured ethyl alcohol. See also: Boater sues over ethanol-laced gasoline's effect on fiberglass fuel tank.
This page shows why Tetrahydrofuran is a good solvent for PVC (polyvinyl chloride).
You can see from the above examples that it really depends on the type of plastic you are trying to dissolve. Each type of plastic has its own chemistry and therefore its own solvents. The easiest way to identify the type of plastic is to use the recycling code. See this page for the codes.
See also Dissolving the Plastics Problem, which talks about dissolving different types of plastic with xylene at higher temperatures.