Polyolefin foams are composed of several materials that have been kneaded together. Typically it involves an organic blowing agent and a cross-linking agent. These come together to make the Polyolefin resin. It is created by thermally decomposing the foaming in a closed system.
Polyolefin is a very general term to describe any compound produced from an olefin as a monomer. Depending on what type of olefin is used, you have different types of polyolefins. For example, if using ethylene as the monomer, you will end up with polyethylene.
It is inexpensive and very light weight and has a wide range of applications. It is often used in the interior casing of airplane and auto parts as well as in the food industry.