PS (PolyStyrene or Styrofoam): it is an amorphous polymer belonging to the family of styrene resins. The standard polymerization gives the product a high transparency (crystal polystyrene GP-PS). It can be found in various applications, especially in the household sector. It works easily with various processing technologies: injection molding, extrusion, thermoforming. Mechanically it has high rigidity even if it tends to be fragile (especially at low thicknesses). The addition of elastomer (rubber) substantially increases the impact resistance (high impact polystyrene HI-PS). The impact polystyrene traditional loses its transparency assuming a whitish color but there are also formulations of transparent HI-PS.