Uses include protective packaging (such as packing peanuts and optical disc jewel cases), containers, lids, bottles, trays, tumblers, disposable cutlery,[6] in the making of models, and as an alternative material for phonograph records.

[11] From storax, the resin of the Oriental sweetgum tree Liquidambar orientalis, he distilled an oily substance, that he named styrol, now called styrene.

[14] About 80 years later it was realized that heating of styrol starts a chain reaction that produces macromolecules, following the thesis of German organic chemist Hermann Staudinger (1881–1965).

[citation needed] The company I. G. Farben began manufacturing polystyrene in Ludwigshafen, about 1931, hoping it would be a suitable replacement for die-cast zinc in many applications.

[16] According to the Science History Institute, "Dow bought the rights to Munters's method and began producing a lightweight, water-resistant, and buoyant material that seemed perfectly suited for building docks and watercraft and for insulating homes, offices, and chicken sheds.

[22] In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating carbon centers are attached to phenyl groups (a derivative of benzene).

When heated (or deformed at a rapid rate, due to a combination of viscoelastic and thermal insulation properties), the chains can take on a higher degree of confirmation and slide past each other.

[citation needed] The relative stereochemical relationship of consecutive phenyl groups determines the tacticity, which affects various physical properties of the material.

Syndiotactic polystyrene resin is currently produced under the trade name XAREC by Idemitsu corporation, who use a metallocene catalyst for the polymerisation reaction.

Like other organic compounds, polystyrene burns to give carbon dioxide and water vapor, in addition to other thermal degradation by-products.

[27] In 2015, researchers discovered that mealworms, the larvae form of the darkling beetle Tenebrio molitor, could digest and subsist healthily on a diet of EPS.

[31] In 2022 scientists identified several bacterial genera, including Pseudomonas, Rhodococcus and Corynebacterium, in the gut of superworms that contain encoded enzymes associated with the degradation of polystyrene and the breakdown product styrene.

Polystyrene Petri dishes and other laboratory containers such as test tubes and microplates play an important role in biomedical research and science.

[59] Water-logging commonly occurs over a long period in polystyrene foams that are constantly exposed to high humidity or are continuously immersed in water, such as in hot tub covers, in floating docks, as supplemental flotation under boat seats, and for below-grade exterior building insulation constantly exposed to groundwater.

Oriented polystyrene (OPS) is produced by stretching extruded PS film, improving visibility through the material by reducing haziness and increasing stiffness.

Polymerization takes place simultaneously in two ways:[64] By using a statistical copolymer at this position, the polymer becomes less susceptible to cross-linking and flows better in the melt.

Styrene can be copolymerized with other monomers; for example, divinylbenzene can be used for cross-linking the polystyrene chains to give the polymer used in solid phase peptide synthesis.

[citation needed] Extruded polystyrene is usually made with hydrofluorocarbons (HFC-134a),[67] which have global warming potentials of approximately 1000–1300 times that of carbon dioxide.

[75] However, legal challenges by the Society of the Plastics Industry[76] kept the ban from going into effect until at last it was delayed when the Republican and Conservative parties gained the majority of the county legislature.

[78] As of 2006, about one hundred localities in the United States, including Portland, Oregon, and San Francisco had some sort of ban on polystyrene foam in restaurants.

[84] Several green leaders, including the Dutch Ministry of the Environment, advise people to reduce their environmental harm by using reusable coffee cups.

The city will introduce bylaw amendments to prohibit business license holders from serving prepared food in polystyrene foam cups and take-out containers, beginning 1 June 2019.

When it is not used to make more EPS, foam scrap can be turned into products such as clothes hangers, park benches, flower pots, toys, rulers, stapler bodies, seedling containers, picture frames, and architectural molding from recycled PS.

A March 2022 joint study by scientists Sewon Oh and Erin Stache at Cornell University in Ithaca, New York found a new processing method of upcycling polystyrene to benzoic acid.

[101] The scientists also demonstrated a similar scalable commercial process of upcycling polystyrene into valuable small-molecules (like benzoic acid) taking just a few hours.

[101] If polystyrene is properly incinerated at high temperatures (up to 1000 °C[102]) and with plenty of air[102] (14 m3/kg[citation needed]), the chemicals generated are water, carbon dioxide, and possibly small amounts of residual halogen-compounds from flame-retardants.

[102][104] When polystyrene was burned at temperatures of 800–900 °C (the typical range of a modern incinerator), the products of combustion consisted of "a complex mixture of polycyclic aromatic hydrocarbons (PAHs) from alkyl benzenes to benzoperylene.

"[105][better source needed] The American National Bureau of Standards Center for Fire Research found 57 chemical by-products released during the combustion of expanded polystyrene (EPS) foam.

[106] The American Chemistry Council, formerly known as the Chemical Manufacturers' Association, wrote in 2011: Based on scientific tests over five decades, government safety agencies have determined that polystyrene is safe for use in foodservice products.

[112] Another Japanese study conducted on wild-type and AhR-null mice found that the styrene trimer, which the authors detected in cooked polystyrene container-packed instant foods, may increase thyroid hormone levels.