Plastics in general are very flammable. Hower they can be modified to be highly temperature and fire resistant. I worked on fire resistant polystyren for TV cases, polyimdies and polyisocyanurate (PIR) - a type of polyurethanes.
Most polymeric materials with best properties are highly crosslined. They are called thermosets and can't be dissolved or melted, which means that they can't be recycled as easily as common packaging plastics. We had experince of recycling thermosets using a new processing technique called purlverasation.
