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Last edited 13 Sep 2023

Polystyrene

Polystyrene is made by stringing together, or polymerising, styrene, a building-block chemical used in the manufacture of many products. Natural styrene occurs in small amounts in foods such as strawberries, cinnamon, coffee, peanuts and beef.

Synthetic styrene, which comprises most of the global styrene, is made from ethylbenzene, which is a monocyclic aromatic hydrocarbon, it is a key product in the petrochemical industry as it produces styrene, used in plastic manufacture, particularly to produce polystyrene.

Other forms of polystyrene are expanded polystyrene (EPS) and extruded polystyrene, which are used extensively in insulation and previously packaging products because buy volume it can be over % air. To produce EPS a blowing agent (also called pneumatogens) is applied to the liquid material, to create a cellular structure, increasing thermal and acoustic insulation, as well as its stiffness whilst reducing density. These blowing agents work in a variety of ways, essentially mechanically, physically, chemically or in combination, some blowing agents have been banned, such as CFCs leading to other approaches, today Pentane is a common blowing agent used in the production of EPS.

To improve its performance in fire flame retardants maybe added, one common one is Hexabromocyclododecane (HBCD) promotes increased fire resistance, particularly in EPS. In the early 2000's HBCD was added to the Stockholm Convention list of on Persistent Organic Pollutants, which started with 12, known as the dirty dozen, later expanded to a little over 20.

Importantly although polystyrene can be classified as either a thermoset plastic or a thermoplastic, EPS and XPS are classified as thermoplastics, meaning they can in theory be melted down and recycled so long as any site contamination and collection issues are overcome.

Polystyrene is a versatile plastic that is used in a number of different forms to make a wide variety of consumer products:

As a hard, solid plastic, it is often used in products that require transparency, such as food packaging and in many products related to medicine and laboratories.
When combined with colourants, additives or other plastics, polystyrene is used to make appliances, electronics, automobile parts, toys, gardening pots and equipment, and so on.
When made into a foam material, called expanded polystyrene (EPS) or extruded polystyrene (XPS), it is valued for its insulating and cushioning properties. Foam polystyrene can be more than 95% air and is widely used to make home and appliance insulation, lightweight protective packaging, surfboards, food service and food packaging, automobile parts, roadway and roadbank stabilisation systems, and so on.