What is Polystyrene

Polystyrene or thermocole as we call it, is a type of polymer made from monomer styrene, extracted as a liquid from petroleum. Polystyrene was discovered in 1839 by Eduard Simon. It is a thermo plastic which means it can be heated and cooled back to a solid. Polystyrene is an aromatic hydrocarbon that participates in covalent bonding with every other carbon atom being attached to a phenol group.

Styrene readily polymerizes to polystyrene by a relatively conventional free radical chain mechanism.

Polystyrene is one of the seven major plastics. Influencing everyday life in a myriad of ways, polystyrene is an invaluable resin. Its recycling code is six.


It is a liquid hydrocarbon i.e. it is composed exclusively of hydrogen and carbon. It is produced via free radical polymerization, which means that the reaction involves breaking the bonds between electrons and leaving them “free” to form new bonds. When burned, polystyrene yields black carbon particles, or soot. When completely oxidized, only carbon dioxide and water vapour remain.

Polystyrene is an odourless, tasteless, rigid thermoplastic. Pure polystyrene has the following structure.

There are several different types of polystyrene produced. Extruded polystyrene is considered to have as much tensile strength as unalloyed aluminium, but is lighter and more elastic. This is the material used to make a variety of moulded products that range from plastic tableware to CD cases and model cars. It is also used to produce medical and pharmaceutical supplies.

Polystyrene has many useful properties. It can be used as an insulator against heat and the cold. It is good at absorbing shocks and protecting delicate items, for example your head when used as part of a cycle crash helmet. Other uses of this polymer are:

  • Protective – IT can absorb shock and keep damage at bay from the materials that are kept in its container.
  • Durable – The exceptional durability of EPS makes it an effective and reliable protective packaging for a wide range of goods. There is no loss of strength in damp conditions, making EPS ideal for cool-chain products. The material is moisture resistant, so the highest hygiene requirements are met. EPS is also odourless and non-toxic.
  • Lightweight – EPS is made up of 98% air, making it a very lightweight material, its use for packaging does not significantly add to the weight of the total product. This in turn means that fuel consumption is improved and fuel emissions are lower than with heavier materials. The reduction in emissions means less impact on global warming.
  • Insulating – The thermal insulation properties of EPS help keep food fresh through the distribution chain. It is widely used to package fresh fish and for seed trays where it assists in the growth of the plants. It is also used by the pharmaceutical industry to package items that are temperature sensitive and that need to be transported around the world.
  • Versatile – EPS can be moulded into any shape or form to meet a product’s protection and insulation needs. Small amounts of EPS can be used as corners for heavy items or a valuable product may be completed encased in EPS to provide maximum protection.