Polystyrene is one of the most common forms of plastic. You see it in coffee cups and egg cartons; it’s the packing material used to cushion goods for shipping. Many call it Styrofoam, though that term is actually the brand name of a rigid blue insulation made by Dow Chemical Company. Polystyrene is a very versatile material, but recycling it isn’t always easy.
Because it’s about 98% air, EPS is an excellent insulator. That’s why it’s used in beer coolers and home insulation, and why the hot coffee in a polystyrene cup doesn’t burn your fingers. Because it’s light, EPS is ideal for creating buoyancy in life vests and rafts. Its lightness and malleability make it a good packing material, adding cushioning but little weight. Also, EPS doesn’t react with other materials and is resistant to heat, so it has found wide use in the food industry in things like meat and poultry trays and the boxes that fast-food hamburgers are served in.
One of the problems of all plastics recycling in general is that you have to gather the same types of materials together and sort them by their material container code. Polystyrene, which is number 6, presents more problems. While water and soda bottles are relatively clean when discarded, polystyrene used for food is often mixed with paper, food scraps and other types of plastic, like the straw that’s thrown away with an EPS cup.
Polystyrene usually can’t be recycled locally but has to be transported to a centralized plant, increasing costs to the recycler and reducing the incentive to recycle. Also, recycled polystyrene cannot in most cases be used for products that contact food because of health concerns, even though the material is usually sterilized by the recycling process. Recycled EPS might be used instead to create packaging or other materials, but new EPS is always needed for coffee cups and plates.