Most electronics cases are made of this form of polystyrene, as are many sewer pipes. 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.
Oriented polystyrene OPS is produced by stretching extruded PS film, improving visibility through the material by reducing haziness and increasing stiffness. This is often used in packaging where the manufacturer would like the consumer to see the enclosed product. The main disadvantage to OPS is that it is brittle, and will crack or tear easily. Polystyrene foams are produced using blowing agents that form bubbles and expand the foam.
In expanded polystyrene, these are usually hydrocarbons such as pentane , which may pose a flammability hazard in manufacturing or storage of newly manufactured material, but have relatively mild environmental impact. Extruded polystyrene is usually made with hydrofluorocarbons HFCa , which have global warming potentials of approximately — times that of carbon dioxide.
Discarded polystyrene does not biodegrade for hundreds of years and is resistant to photo-oxidation. Animals do not recognize polystyrene foam as an artificial material and may even mistake it for food.
Polystyrene foam blows in the wind and floats on water, due to its low specific gravity. It can have serious effects on the health of birds or marine animals that swallow significant quantities. Restricting the use of foamed polystyrene takeout food packaging is a priority of many solid waste environmental organisations. Efforts have been made to find alternatives to polystyrene, especially foam in restaurant settings.
The original impetus was to eliminate chlorofluorocarbons CFC , which was a former component of foam. Bottom of a vacuum-formed cup; note how fine details such as the glass and fork food contact materials symbol and the resin identification code symbol are easily molded. Polystyrene facts for kids Kids Encyclopedia Facts. Quick facts for kids. All content from Kiddle encyclopedia articles including the article images and facts can be freely used under Attribution-ShareAlike license, unless stated otherwise.
Cite this article:. This page was last modified on 24 September , at Suggest an edit. Solubility in water. Refractive index n D. Tensile strength s t. Coefficient of thermal expansion. Polystyrene is used for the housing and other parts for televisions, computers and all types of IT equipment, where the combination of form, function and aesthetics are essential. Polystyrene foodservice packaging typically insulates better, keeps food fresher longer and costs less than alternatives. Lightweight polystyrene foam provides excellent thermal insulation in numerous applications, such as building walls and roofing, refrigerators and freezers, and industrial cold storage facilities.
Polystyrene insulation is inert, durable and resistant to water damage. Due to its clarity and ease of sterilization, polystyrene is used for a wide range of medical applications, including tissue culture trays, test tubes, petri dishes, diagnostic components, housings for test kits and medical devices. Polystyrene solid and foam is widely used to protect consumer products. In the United States, the U. Food and Drug Administration FDA strictly regulates all food packaging materials, including polystyrene.
For every material used in food contact, there must be sufficient scientific information to demonstrate that its use is safe. Tiny amounts of styrene may remain in polystyrene following manufacture, so FDA has evaluated both the safety of the food contact material itself polystyrene and the safety of the substance that may migrate styrene.
The result of these evaluations: FDA for decades has determined that polystyrene is safe for use in contact with food. The U. National Toxicology Program Director Dr.
Linda Birnbaum, Ph. The data show that current exposures to styrene from the use of polystyrene food contact products remain extremely low, with the estimated daily intake calculated at 6. Public health officials encourage the use of sanitary, single-use foodservice packaging such as polystyrene in appropriate settings.
Single-use foodservice packaging can help reduce food-borne illness in homes, hospitals, schools, nursing homes, cafeterias and restaurants. FDA has for decades stated that polystyrene is safe for use in contact with food. From to , a member international expert panel selected by the Harvard Center for Risk Analysis conducted a comprehensive review of potential health risks associated with workplace and environmental exposure to styrene.
The scientists reviewed all of the published data on the quantity of styrene contributed to the diet due to migration from food contact packaging. The scientists concluded that there is no cause for concern from exposure to styrene from food or from polystyrene used in food contact applications, such as packaging and foodservice containers. Styrene occurs naturally in many foods and beverages. A U. Environmental Protection Agency study found styrene residues, however infinitesimal, in percent of the human fat tissue samples taken.
Styrene toxicity may be much greater for people exposed occupationally or via air pollution. Cells from broken-down styrofoam find their way into streams, lakes and oceans. There, they may be consumed by fish and other marine and aquatic animals , who easily mistake them for food. This is not good for the sea creatures they may choke or starve , nor for the creatures who consume them — which may ultimately include us humans. Another environmental issue may arise from the blowing agents used to foam EPS.
In the past, some fluorinated hydrocarbon gases were used because of their stability. More recently, their effects on the ozone layer or global warming have prompted a shift to substitutes.
It may still be a problem there. One issue is volume. Styrofoam takes up a lot of room per unit of weight. Remember that as foam it has been expanded to times its original volume. A lot of landfills are running out of room. One common estimate is that styrofoam can take up 30 percent of the space in some landfills.
Once in the landfill, it does not decompose quickly. Some estimates put the lifespan of styrofoam in a landfill around years , and some put it way beyond that. Of course, some fraction of all discarded styrofoam does not go into landfills. Some estimate that fraction at 20 percent , at least in the United States. A lot of that is just littered around the landscape, and a lot of that ends up in water.
It does not biodegrade. It is chemically stable, and bacteria and microorganisms do not feed on it. It is common wisdom that styrofoam can not be recycled, which is not true in a very technical sense.
It is true that the vast majority of municipal recycling programs will not accept it. But there are a few facilities that will take it. One reason is that most styrofoam waste think carryout food containers is not clean and cannot be easily cleaned.
A second important reason is that nobody can make any money recycling styrofoam. Ordinary hard, unexpanded, polystyrene is common in commercial use — an example may be that yogurt or sour cream container in your refrigerator. It will have the triangular recyclable logo on it and the number 6, meaning polystyrene. Clean these and recycle them.
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