Polystyrene packing comes in many forms. A polymer made up of many styrene molecules bound together in long chains, polystyrene is one of the most common plastics. Various forms of polystyrene are used to manufacture thousands of different products from razors to compact disc cases and electronic component cases. Most polystyrene packing is made from polystyrene foam. It is one of the most common and popular packing materials in use today because of its light weight and superb shock absorption qualities.
Air or some other gas is often injected into polystyrene in its liquid form, creating a foam, which is then molded or extruded. Polystyrene foam is widely manufactured and is produced by Dow Corporation under the trademark name Styrofoam®, which is the name often used for any polystyrene foam. Foam packing made from polystyrene is often molded into complex shapes to stabilize objects or products within a corrugated cardboard box. Molding technologies allow for these polystyrene packing materials to be designed and constructed using voids in the rectangular polyhedron shape of most boxes to reduce the amount of material needed for the packing, while keeping an irregular object stabilized and protected.
Simple polystyrene foam boards are another common type of polystyrene packing. These boards are easy and cheap to produce and are often used to pack regular rectangular or square solid shapes within a cardboard box. Polystyrene foam boards are commonly between 1 and 2 inches (2.5 to 5 cm) thick.
Polystyrene packing chips are a very cheap and common type of polystyrene packing material. They are made from irregular, wafer-shaped chunks of extruded polystyrene foam and come in a large variety of sizes and shapes. Packing "peanuts" are another type of polystyrene packing, also made from extruded polystyrene foam. A very common packing material, they are named for their shape, which resembles a peanut, or sometimes an "S". Packing peanuts and packing chips are often used to completely fill the area around an irregular object within other packaging such as a cardboard box.
Some types of polystyrene packing are constructed solely of polystyrene. Polystyrene foam boxes are often used to ship foods and other goods requiring refrigeration. Ice, chemical cold packs, or dry ice is placed inside the box with the food or product. Polystyrene foam's excellent insulating qualities ensure that the product stays cold during shipping. Light-weight, thin-walled foam boxes are commonly used in restaurants for take-out or delivery of prepared foods.