Polystyrene vs. Styrene

What Makes Polystyrene so Different from Styrene? Itís a Matter of Chemistry.
By American Chemistry Council

The United States National Academy of Sciences (NAS) has released its review of the United States National Toxicology Program’s (NTP) June 2011 decision to include styrene in its 12th Report on Carcinogens (RoC).

In reviewing the NAS findings, it’s important to understand the differences between the two. Styrene, a liquid, and polystyrene, a solid, are fundamentally different. Styrene is a liquid that can be chemically linked to create polystyrene, which is a solid plastic that displays different properties.

Polystyrene is used to make a variety of important consumer products, such as foodservice containers, cushioning for shipping delicate electronics, and insulation. Although the names sound familiar and may be confusing, styrene and polystyrene are different and have completely different properties.

Polystyrene’s safety profile is so strong that the United States Food and Drug Administration (FDA) has reviewed the safety of polystyrene to be used in direct contact with foods and beverages – and for 50 years, has confirmed polystyrene to be safe for this use. The NTP agrees that the safety of polystyrene in foodservice is not in question – pointedly saying that the safety of styrene is “not an issue.”

Two different chemistries

The Basics: When styrene molecules become linked together into a polymer, polystyrene is created. Polystyrene is an inert plastic that can be used to make many products, such as polystyrene foam used to make disposable plates, cups and other foodservice packaging products.

How It’s Used: Polystyrene is used in many applications. One application is foodservice – polystyrene foam is a clean and affordable option to insulate food and to keep it fresher for a longer period of time. Polystyrene foam is a lightweight material, about 95% air, with very good insulation properties and is used in many types of products, such as cups that keep your beverages hot or cold. Polystyrene foam is also widely used in cushioning or protective packaging that helps keeps computers and appliances safe during shipping. Most people incorrectly use the name STYROFOAM® to refer to polystyrene; STYROFOAM® is a registered trademark of The Dow Chemical Company that refers to its branded building material products.

The Basics: Styrene is a clear, colorless liquid that is a component of materials used to make thousands of everyday products. Styrene occurs naturally in many foods, such as cinnamon, beef, coffee beans, peanuts, wheat, oats, strawberries and peaches. Synthetic styrene, which is chemically identical to naturally occurring styrene, is manufactured as a chemical building block for materials used to make packaging, insulation, automobiles, electronics, boats, and recreational vehicles.

How It’s Used: For more than 70 years, styrene has been used a chemical building block used to manufacture many familiar products, such as food containers, rubber tires, building insulation, carpet backing and reinforced fiberglass composites such as boat hulls, surfboards, residential kitchen countertops, bathtubs and shower enclosures.



About XPSA

The Extruded Polystyrene Foam Association (XPSA) is a trade association representing manufacturers of Extruded Polystyrene Foam (XPS) insulation products and the industry's raw material suppliers. XPSA members collectively manufacture more than 95% of all XPS destined for use in the North American market. XPSA promotes the benefits that accrue to society from appropriate use of XPS foam insulation applications.

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