This substance class also contains, besides EPP, the products made of polyethylene (EPE) and polystyrene (EPS). The history started with the discovery of polystyrene in 1950, when BASF scientists succeeded in impregnating PS-pellets with a hydrocarbon as propellant and in welding it to foam by heating. On February 28th, 1952, the "Procedure to manufacture porous masses out of polymers" was patented - the fundamental patent for the production of expandable polystyrene. About 20 years later, this principle was also applied on polyethylene in search of foam with special attributes; at the beginning of the 80´s it was applied on polypropylene too.
The particle-foams cover a wide spectrum of characteristics and therewith different areas of application.