GPPS is polystyrene for general use, is an entirely transparent ("limpid"), but also fragile material, widely used in the production of food packaging and CD / DVD boxes.
HIPS is a versatile, economical and high impact-resistant plastic. It is smooth to machine and manufacture. HIPS is also often destined for low strength structural applications where impact resistance, machinability and low cost are required.
Another important example of thermoforming polystyrene is the production of interior coatings for refrigerators and freezers. Specially developed grades of HIPS with increased resistance to stress corrosion resistance (ESCR) have been developed.