Polystyrene (Styrofoam). Thermoplastic resin obtained by polyaddition of styrene. There are various kinds of this material, the most common are the PS (crystal) homopolymer amorphous, transparent; HIPS (impact resistant) modified with rubber, EPS (expandable) pentane is used as an agent expandable; XPS (foam) extruded and expanded; BOPS (biaxially oriented) bi-oriented leaf. The second raw material is mainly obtained from processing scraps and production waste recycling (pre-consumer) and packaging and containers recycling (post-consumer). Degradation processes occours when PS is subjected to high temperatures machining, high mechanical stress, high times of resistance and to oxygen presence.