Drying : Polystyrene (PS) plastic is a naturally transparent thermoplastic that is available as both a typical solid plastic as well in the form of a rigid foam material. Expanded polystyrene (EPS) is a widely used foam-like plastic material. Its main purpose can be found in building and construction applications. Also particularly useful for commercial packaging. The Fluid Bed Dryer/cooler separates the unnecessary water from the polymer beads.