Styrene is an organic hydrocarbon used to manufacture rubber and plastic components. Also known as vinyl benzene, styrene is a colorless liquid that quickly evaporates when exposed to the air. Although it is an aromatic monomer with a slightly sweet smell, its odor can be unpleasant in high concentrations or when mixed with other chemicals. If its molecules become linked to form long chains of styrene, it becomes polystyrene, an aromatic polymer with thermoplastic properties.
While styrene is manufactured from petroleum on a commercial scale, it also occurs naturally in certain plants, including fruits, nuts, and vegetables. In fact, it received its name in honor of the Styrax genus of trees that produce a sap from which benzoin resin is obtained. Its alternate name of vinyl benzene likely stems from the fact that it is synthesized from ethylbenzene, which is the product of benzene and ethylene being subjected to catalytic dehydrogenation. Styrene molecules also contain a vinyl group (ethenyl) that share electrons in a reaction known as covalent bonding. This process is what allows the synthetic chemical to be made into plastics, such as polystyrene, synthetic rubber, and latex.
During World War II, styrene production was at its peak in the U.S. due to a need for synthetic rubber, as the majority of natural rubber producing areas were held by the Japanese at the time. A substitute was secretly made by producing a copolymer of butadiene and styrene known as Government Rubber Styrene (GRS). By the mid-1940s, GRS production exceeded twice the level of natural rubber production prior to the onset of the war. During the war, this material was primarily used to make tires for the military. However, this invention stayed the course since GRS is still used in the manufacturing of all types of tires in the U.S. today.
In other industries, styrene is used to make all sorts of products ranging from shoes to rubber backing for carpets. However, this material is also used to manufacture parts for cars and boats, plumbing pipes, fiberglass, insulation, some building materials, and electrical components. It is also used to make plastic drinking cups and food storage containers.
Styrene has little, if any, environmental impact since it quickly degrades in the open air and evaporates from soil and water. However, certain health hazards of styrene have been noted. For one thing, the International Agency for Research on Cancer considers styrene to be a suspected carcinogen. Other than direct handling, exposure to this substance may occur from inhaling automobile exhaust, cigarette smoke, and being around building materials that contain styrene. In addition, styrene may be released when using a photocopy machine or leached when eating foods packed in a polystyrene container.
By Karyn Maier