About Polystyrene. Polystyrene (a.k.a. PS, Thermocol), a thermoplastic polymer with a high molecular weight, is manufactured from the styrene monomer. This material, commonly referred to as PS, exhibits characteristics of hardness, rigidity, and exceptional transparency, accompanied by commendable chemical resistance. Due to its versatility, polystyrene finds extensive application and ranks among the most widely produced polymers globally. The prevailing form of commercialized polystyrene is known as General Purpose Polystyrene (GPPS), though it is also available as Expandable Polystyrene (EPS) and High Impact Polystyrene (HIPS). Scrap polystyrene also has its value on the market. Additionally, the polymer lends itself to easy processing through techniques such as injection molding, extrusion, and thermoforming.

The styrene can be polymerized to Polystyrene by anionic, cationic, free-radical, and Ziegler-Natta mechanisms, however most industrial production of Polystyrene is based on free-radical polymerization due to simpler process configuration (less/no requirements in terms of monomer purification and initiator residues removal). In fact, while styrene itself can form polymerization-initiating radicals, radical-forming initiators do not necessarily have to be used for styrene polymerization.

In addition to the different reaction mechanisms, polystyrene production can also differ according to the technological route employed: solution, suspension or mass (bulk) polymerization. The solution route is favored when polymers with low residual monomer content and high purity are desired. The suspension route, on the other hand, facilitates the creation of polymers with varying molecular weights, allowing for the production of specialized crystal and high-impact grades of PS. Lastly, bulk polymerization offers advantages such as the clarity and outstanding color of the resulting resins, being the preferred method for most industrial units.

Polystyrene Handling. The storage and transportation of Polystyrene does not pose problems, as there are no specific regulatory issues regarding its transport. This polymer can be transported in paper or polyethylene bags, in cardboard containers, in silo vehicles, or in containers. In the case of Expandable Polystyrene (EPS), the storage should be made in a well-ventilated place, since pentane can naturally evolve from EPS as a gas into the atmosphere and is flammable at low concentrations (1.3% volume in air).

Polystyrene Production. Polystyrene production consists in the polymerization of styrene, in such a way that different manufacturing routes are related to different sources of such raw material. In this context, Polystyrene production routes can be based on styrene derived from ethylbenzene, toluene and methanol, benzene and ethylene. Raw materials and the respective production processes employed in the manufacturing of Polystyrene are listed below.

Polystyrene Uses. The uses and applications of Polystyrene may vary according to its specification. The main forms of Polystyrene are General Purpose Polystyrene (GPPS); High Impact Polystyrene (HIPS); Expandable Polystyrene (EPS), in the forms of molded foam; expanded beads; and resins.

There is competition from other plastics and materials. For instance, in the realm of food packaging, certain manufacturers have transitioned to options like paper. In the consumer electronics sector, alternative plastics like acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) have supplanted a portion of the usage of polystyrene (PS).