Polystyrene is one of the most common types of plastic. Due to its versatility, it is widely used in the manufacture of various products. It is especially well-suited for packaging and laboratory items, because it is durable and resilient but clear at the same time. It can be mixed with other plastics or combined with additives or colorants. It can be used in the production of gardening equipment, electronics, automobile parts, toys, household appliances and many others.
Expanded polystyrene (EPS) and extruded polystyrene (XPS) are two types of foam produced from polystyrene that are used in large amounts as insulating and cushioning materials. The content of air in foam polystyrene is of over 95 percent. This makes it perfect for the manufacture of various products like protective packaging, surfboards, foodservice and food packaging, automobile parts, roadway or road bank stabilization systems and insulation for homes and appliances.
Just like its name implies, polystyrene is a string (polymer) of styrene, which is a basic chemical compound that serves as a building block in the structure of many products. Cinnamon, strawberries, coffee and even beef meat are natural sources of styrene.
Eduard Simon, a pharmacist from Berlin, was the first to discover polystyrene in 1839. He isolated it by distillation from the resin of the American sweet gum tree Liquidambar styraciflua, also known as storax. He gave the name styrol to the monomer with an oily consistency that resulted. After a few days, he discovered that the initial substance became similar to a jelly. He blamed it on oxidation, so he named it Styroloxyd, or styrol oxide.
John Buddle Blyth, a chemist born in Jamaica, and German chemist August Wilhelm von Hofmann continued the work. They were both able to prove by 1845 that styrol transforms even if oxygen is not present. Even if the compound was identical to Eduard Simon's Styroloxyd, it was given the different name "metastyrol". The transformation process was correctly identified for the first time as polymerisation by Marcelin Berthelot in 1866. It took another 80 years until the thesis of German organic chemist Hermann Staudinger(1881 - 1965) established that styrol starts a chain reaction when heated, producing macromolecules. The compound was later re-named polystyrene, which remained unchanged to this day.
German industrial giant I. G. Farben started to produce polystyrene in 1931 in a facility in Ludwigshafen. They attempted to use it as an alternative to die-cast zinc parts that were used in many products. They managed to produce polystyrene pellets using a reactor recipient that relied on a heated tube and a cutter to extrude polystyrene. The styrofoam process was developed and patented by Dow Chemical in 1941.
After the Second World War, an engineer named Fritz Stastny (1908-1985) included pentane and other aliphatic hydrocarbons into the beads, developing pre-expanded polystyrene. The resulting raw material is the one used to extrude sheets or mold various parts. The patent for this technology was registered in 1949 by Stastny and German giant BASF. The first products were sold as Styropor and the initial demonstration of the moulding technique took place in 1952 at the Kunststoff Messe in Düsseldorf.
Giulio Natta later contributed by describing the crystal structure of isotactic polystyrene. Expanded polystyrene (EPS) foam was invented in 1954 and sold under the brand by the Dylite Koppers Company, based in Pittsburgh, Pennsylvania. The first foam cups were delivered by the Dart Container Company in 1960.
There are three major types of polystyrene. Besides the normal polystyrene in plastic form, the other two are polystyrene foam and polystyrene film. There are two main types of foam: expanded polystyrene (EPS) and extruded polystyrene (XPS). The most common polystyrene applications are made from EPS and include for example packing peanuts or styrofoam. Because of the higher durability and density, XPS foam is more common in architecture and constructions. Copolymers can also be found among the polystyrene types. One example is HIPS, or High Impact Polystyrene, which is a copolymer that combines polystyrene with other materials in order to make it less brittle and more durable on impact. A widespread packaging material is polystyrene film, which can be easily vacuumed. Oriented polystyrene (OPS) is also produced from film and is cheaper than PP and other alternatives.
Just like most plastics, the raw materials used in the production of polystyrene are hydrocarbon fuels. These are distilled into components known as fractions that transform into plastics after reacting with some catalysts. A process of polymerization is initiated to produce polystyrene. In order to manufacture foam, special agents are inserted into polystyrene and later expand, trapping a large amount of air in its composition.
Foam is probably the most common application of polystyrene. It is widely used in packaging but is also a very versatile material in its traditional form as a plastic. Another unique use of polystyrene is the production of various prototypes, for which it was for many years the best quality material. It is a very cheap material that is available in large quantities. It has a white color and can be easily painted, cut or glued according to needs.
Many home appliances are produced with polystyrene. It is great for this purpose because it doesn't react with other materials, being completely inert, as well as durable and cheap. Polystyrene is found in items such as microwaves, vacuum cleaners, blenders, refrigerators, air conditioners and ovens.
Both polystyrene foam and solid plastic are used in the automotive industry. Foam is needed for sound dampening and energy absorbing door panels, while plastic is used for trims, knobs and instrument panels. Protective seats for children are also made from foam polystyrene.
Polystyrene is also very suitable for electronics, due to a good mix of durability and function. It is very common in the housing and other parts of computers, IT equipment, television sets and various other products.
It is the best material for food packaging, due to the very low price and quality insulation. Polystyrene packaging keeps food fresh for longer than other alternative materials.
Polystyrene foam has a low weight and great insulation qualities. This makes it very suitable in construction as a thermal proofing material. It is part of roofs and walls but also serves the same purpose in cold storage facilities, freezers and refrigerators. It resists shocks and water damage while being chemically inert.
This type of plastic also has many applications in medicine. Its main advantages are the ease of sterilization and the clear texture. Many items are made of polystyrene, including diagnostic components, housings for test kits and other medical devices, including tissue culture trays, test tubes and petri dishes.
All forms of polystyrene are very common in packaging, providing protection to various products. The popular package "peanuts" used in shipping are made of polystyrene, as well as food packaging, meat/poultry trays, CD cases or egg cartons. Sometimes the plastic is combined with other materials.