This standard specifies expandable polystyrene foam used as package cushioning material. It does not cover polystyrene foam in chip or granular form. The foam shall consist of closed-cell, expanded polystyrene particles. The particles are bonded tightly to each other.
SS 357 Pt.1-1991 history
1991SS 357 Pt.1-1991 SPECIFICATION FOR Cushioning Foams Part 1 : Polystyrene