Foam Polystyrene Production Process

Polystyrene (PS) is a multi-faceted plastic used in many common items. The resin identification code for this plastic is "6." PS (solid or foamed) starts as a liquid monomer and is made into a stable, solid polymer pellet. To turn the pellets into PS foam, they are impregnated with a blowing agent, such as pentane or carbon dioxide. This transforms them into “pre-puff” beads. The beads are then heated and puffed up like popcorn. These beads are made into cups, plates, and containers through thermoforming or steam-chest molding.