Is black foam a good insulator?

Answer 1

Polystyrene foam is a good insulator.

The characteristics that make polystyrene is a good insulator stems from its composition of long polymer chains and because it encapsulates regions of gas in the form of a closed cell foam. Air and gas in general are poor conductors of hear when convection is inhibited as it is in a foam. (The form used in insulation is often a closed cell foam, but that is not the only form taken by polystyrene.)

Answer 2

The color is probably quite secondary. In any case, I am pretty sure that there are lots of materials that are black, and have a foam structure. You need to clarify what specific material you are talking about. You should also clarify whether you are talking about electrical or heat insulator - though the two often go together. For example, some polymer (which one?) - polymers are often good insulators. A material with a form structure is often a good insulator against heat, though - depending on the specific material - it may or may not be a good electrical insulator.