This weak force accounts for many of polystyrene's characteristics such as flexibility. The scientists had expertise in toxicology, epidemiology, medicine, risk analysis, pharmacokinetics, and exposure assessment. 1) Buna-S(styrene butadiene rubber)- It is obtained by the polymerization of Buta-1,3-diene & styrene in the ratio of 3:1 in the presence of sodium.It is used for making automobile tyres & footwear. Structurally, it is a long hydrocarbon chain, with a phenyl group attached to every other carbon atom. materials, styrene monomer will react with itself to form a homopolymer. monomer molecules. [45] In expanded polystyrene there are interstitial gaps between the expanded closed-cell pellets that form an open network of channels between the bonded pellets, and this network of gaps can become filled with liquid water. Polystyrene is the packaging material of choice, because it is light and cool. Here ethylene (ethene) is the monomer, and the corresponding linear polymer is called high-density polyethylene (HDPE). [66] 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. The monomer is present throughout the polymerization but it decreases gradually. • Polymers, both natural and synthetic, are created via polymerization of many … This causes physical cross-linking on a microscopic level. [78], China banned expanded polystyrene takeout/takeaway containers and tableware around 1999. It is an inexpensive resin per unit weight. It becomes rigid again when it cools down. Several copolymers are used based on styrene: The crispiness of homopolymeric polystyrene is overcome by elastomer-modified styrene-butadiene copolymers. This weak force accounts for many of polystyrene's characteristics such as flexibility. Polystyrene can be solid or foamed. Table 1 also shows the basal spacing of org-MMTs and PS/MMT hybrids, and the difference(∆d) of basal spacings between them. Images of the chemical structure of STYRENE are given below: The 2D chemical structure image of STYRENE is also called skeletal formula, which is the standard notation for organic molecules. [97], Whether polystyrene can be microwaved with food is controversial. The process converts used polystyrene products back into their original liquid form – styrene monomer. Mealworms are the answer! [52]:476, SBS (styrene-butadiene-styrene block copolymer) is made by anionic block copolymerization and consists of three blocks:[54], SSSSSSS­SSSSSSS­SSSSSSBBBBBBB­BBBBBBB­BBBBBBSSSSSSS­SSSSSSS­SSSSSS. Polystyrene Synthesis‎ Background In this lab, the polystyrene is made by chain-growth polymerization. Styrene is employed in the manufacture of polystyrene, an important plastic, as well as a The formation of each lamella contributes to the consumption of energy and thus to an increase in elongation at break. [69] In 1988, the first U.S. ban of general polystyrene foam was enacted in Berkeley, California. It is produced by polymerization of styrene in the presence of polybutadiene dissolved (in styrene). [92], Polystyrene is commonly used in containers for food and drinks. This derivative of benzene is a colourless oily liquid that evaporates easily and has a sweet smell, although high concentrations confer a less pleasant odour. It is used in packaging consumer goods such as DVD cases, egg cartons, to protect against spoilage or damage. S represents in the figure the styrene repeat unit, B the butadiene repeat unit. Polystyrene is compound is non-biodegradable with a couple of exceptions. These repeating units are “monomers”. However, the polyblend material has considerably worse properties. monomer, i.e., class name:monomer name. [59] [86][88], 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. The molecular weight increases at a Glyptal is made up of monomers ethylene glycol and phthalic acid. Poly (1-phenylethane-1,2-diyl), Poly (1-phenylethylene) ACRONYMS. Polymers formed by a straightforward linking together of monomer units, with no loss or gain of material, are called addition polymers or chain-growth polymers.A listing of some important addition polymers and their monomer precursors is presented in the following table. 2.3.1.2 Branched Polymers The benzene group in this compound is then dehydrogenated to yield phenylethylene, or styrene, a clear liquid hydrocarbon with the chemical structure CH 2 =CHC 6 H 5. When we are looking at polymers it is often useful to know what individual pieces makes up this polymer. Chain-growth polymerization involves the polymer growing by adding monomers on to the ends of the chain of the polymer. The polystyrene produced by mass polymerization is a fully transparent, atactic, low cost thermoplastic known as general purpose polystyrene (GPPS) or crystal-clear polystyrene. [53] Unlike PS-I and SBC, it is not a thermoplastic, but an elastomer. Because polystyrene contains only carbon hydrogen bonds, it is non-polar and can dissolve only in non-polar solvents, much as dissolves. polystyrene (PS) Ultra-High Molecular Weight Polyethylene (UHMWPE) ... manner by which monomers are converted into polymers as they are joined together by covalent bonds. Commonly extruded polystyrene foam materials include: Although it is a closed-cell foam, both expanded and extruded polystyrene are not entirely waterproof or vapor proof. At room temperature and pressure, styrene is a clear, colorless liquid.Other names for styrene can be styrol, vinylbenzene, phenylethene, or phenylethylene. example, depending on the method of polymerization, polystyrene may exhibit isotactic, syndiotactic or atactic structure, as shown in Fig. Polystyrene: The reaction is the same for polystrene where every other carbon has a benzene ring attached. Polystyrene became one of the most widely used plastics, especially during the World War II. The urea-formaldehyde resin is a non-transparent plastic obtained by heating formaldehyde and urea. a polymer consisting of all the same monomer The carb… Polystyrene is a hard, brilliantly transparent, stiff resin. Polystyrene is an odorless, tasteless, rigid thermoplastic. The general starch structure is depicted below. [81] They thereby scatter visible light, making PS-I opaque. The individual pieces to make up the polymer are called monomers. Restricting the use of foamed polystyrene takeout food packaging is a priority of many solid waste environmental organisations. In contrast to PS-I, however, the block copolymer does not form any particles but has a lamellar structure. Because of the amount of heat released, it is sometimes used as a power source for steam or electricity generation. Both processes can be carried out in batch or continuously. Styrene is a certain organic chemical compound having the chemical formula C 8 H 8.Its chemical structure is made up of a vinyl group bonded onto a benzene ring. This benzene ring makes styrene an aromatic compound. Its range of applications is further extended by copolymerization and other modifications (blends e.g. Polystyrene contains the toxic substances Styrene and Benzene, possible carcinogens and neurotoxins that are harmful to humans. Polyvinyl chloride (PVC) is a plastic polymer made of monomer vinyl chloride. Polystyrene is also a very strong insulator which means that it accumulates electrical charge easily. What is Polystyrene? and Govaert, L.E. Water vapor diffusion resistance (μ) of XPS is around 80–250. Addition reaction mechanism showing styrene monomer polymerizing into polystyrene. Please select Monomer products to review from categories in the left navigation menu. The key difference between polystyrene and polypropylene is that the monomer for polystyrene is styrene, while the monomer for polypropylene is propylene.. Polymers are large molecules, which have the same structural unit repeating over and over. [58], Animals do not recognize polystyrene foam as an artificial material and may even mistake it for food. Polystyrene Synthesis‎ Background In this lab, the polystyrene is made by chain-growth polymerization. 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. The monomer is present throughout the polymerization but it decreases gradually. Starch contains bonds of oxygen carbon and oxygen hydrogen which make it a polar molecule. Styrene-butane co-polymers can be produced with a low butene content. The repeating structural unit of most simple polymers not only reflects the monomer(s) from which the polymers are constructed, but also provides a concise means for drawing structures to represent these macromolecules. Polystyrene (PS) is recyclable plastic #6. Required fields are marked *. If the water freezes into ice, it expands and can cause polystyrene pellets to break off from the foam. PS-I (impact resistant polystyrene) consists of a continuous polystyrene matrix and a rubber phase dispersed therein. The most important monomers for this process are ethylene (which makes the polymer polyethylene) and substituted ethylenes like vinyl choride (polyvinyl chloride), styrene (phenylethylene, polystyrene), methyl methacrylate (Plexiglas), and acrylonitrile (cyanoethylene, acrylic fibers). 5. The STYRENE molecule contains a total of 16 bond(s) There are 8 non-H bond(s), 7 multiple bond(s), 1 rotatable bond(s), 1 double bond(s), 6 aromatic bond(s) and 1 six-membered ring(s). For the production of SBS, the first styrene is homopolymerized via anionic copolymerization. Polystyrene is produced by free radical vinyl polymerization, from the monomer styrene. [66], On July 1, 2015, New York City became the largest city in the United States to attempt to prohibit the sale, possession, and distribution of single-use polystyrene foam (the initial decision was overturned on appeal). The main difference between styrene and polystyrene is that the styrene is a monomer, whereas polystyrene is a polymer. [57], Waste polystyrene takes hundreds of years to biodegrade and is resistant to photo-oxidation. A large number of cracks give the originally rigid material a laminated structure. Polystyrene is a vinyl polymer. This is a better picture of what the monomer styrene looks like: Go ahead, play with it! Copolymers of styrene and acrylonitrile (SAN) are more resistant to thermal stress, heat and chemicals than homopolymers and are also transparent. The molecular weight increases at a Monomers bind with each other via covalent bonds to form a polymer. Many polymeric materials having chain-like structures similar to polyethylene are known. Styrene-butadiene rubber (SBR) is produced like PS-I by graft copolymerization, but with a lower styrene content. A polymerization reaction starts with a primary ingredient (monomer), such as ethylene or propylene. Styrene monomer will react with a variety of other monomers to form a number of copolymers. 4. Polyvinyl chloride (PVC) is a plastic polymer made of monomer vinyl chloride. These are written in italic font. Typically linear polymers are made from monomers with single end group. [65] In the meantime, Berkeley became the first city to ban all foam food containers. PS can also be prepared by solution and suspension techniques. 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.[83]. The reaction used to form polystyrene in this lab is shown in FIG. In 1987, Berkeley, California, banned CFC food containers. The key difference between polystyrene and polypropylene is that the monomer for polystyrene is styrene, while the monomer for polypropylene is propylene.. Polymers are large molecules, which have the same structural unit repeating over and over. Atactic polystyrene is entirely 7 due to copyright restrictions. [62] The following year, Suffolk County, New York, became the first U.S. jurisdiction to ban polystyrene in general. [86] If only incomplete incineration is done, there will also be leftover carbon soot and a complex mixture of volatile compounds. [70] In San Francisco, supervisors approved the toughest ban on "Styrofoam" (EPS) in the US which went into effect January 1, 2017. Polystyrene became one of the most widely used plastics, especially during the World War II. Polystyrene is an aromatic polymer, naturally transparent, made up of monomer styrene. POLYMER CLASS. Polystyrene foam blows in the wind and floats on water, due to its low specific gravity. (2003), BASF Technische Information TI 0/2-810d 81677 Juni 1989, Verwertungs- und Beseitigungsverfaren gebrauchter Schaumstoff-Verpackungen aus Styropor®, "Common Plastic Resins Used in Packaging", "Ueber das Stryol und einige seiner Zersetzungsproducte", "Sur Les caractères de la benzine et du styrolène, comparés avec ceux des Autres carburetors d'hydrogène", "Styrofoam, a Practical and Problematic Creation", "Celebrating 50 Years of Excellence in People and Products", "XAREC Syndiotactic Polystyrene – Petrochemicals – Idemitsu Kosan Global", "Plastic-eating worms may offer solution to mounting waste, Stanford researchers discover", "Think you can't compost styrofoam? materials, styrene monomer will react with itself to form a homopolymer. The polystyrene produced by mass polymerization is a fully transparent, atactic, low cost thermoplastic known as general purpose polystyrene (GPPS) or crystal-clear polystyrene. Styrene-butadiene rubber behaves like an elastomer but can be processed like a thermoplastic. A chemical structure of a molecule includes the arrangement of atoms and the chemical bonds that hold the atoms together. Polystyrene chains are made from many styrene molecules. Polybutadiene is a homopolymer (only one monomer) of 1,3 butadiene, a monomer containing four carbon atoms, and six hydrogen atoms (C 4 H 6). American manufacturers have produced insulating concrete forms made with approximately 80% recycled EPS since 1993. DVB has vinyl groups (-CH=CH 2 ) at each end of its molecule, each of which can be polymerized into a polymer chain like any other vinyl group on a styrene monomer. Such variety offers the synthetic chemist tools to make a rich array of polymer compositions. COMMON NAMES. It is produced by the polymerization of styrene and is the most widely used plastic. Techniques have been developed which increase its mechanical strength, its ability to absorb shock and its thermal insulating properties. [95] Styrene oligomers in polystyrene containers used for food packaging have been found to migrate into the food. Polystyrene homo-polymers deform when a force is applied until they break. Polystyrene with DVB: Cross-linking between polymer chains can be introduced into polystyrene by copolymerizing with p-divinylbenzene (DVB). Figure 2. [72] Several green leaders, from the Dutch Ministry of the Environment to Starbucks's Green Team, advise people to reduce their environmental harm by using reusable coffee cups. Polystyrene is a long chain hydrocarbon and is written as C8H8. Styrene-butane co-polymers do not break at this point, but begin to flow, solidify to tensile strength and only break at much higher elongation.[50]:426. It becomes rigid again when it cools down. You can then unwind this piece of thread, and have an individual thread piece. Styrene, also... Styrene is obtained by reacting ethylene with benzene in the presence of aluminum chloride to yield ethylbenzene. Styrene, liquid hydrocarbon that is important chiefly for its marked tendency to undergo polymerization (a process in which individual molecules are linked to produce extremely large, multiple-unit molecules). The role of monomer in the structure regulation of PS particles As described in the previous section, the monomer/seed ratio was set as 4.0 in recipe 2 for sufficient swelling to the seed particles. Monomers bind with each other via covalent bonds to form a polymer. In May 2019, Maryland Governor Hogan allowed the foam ban (House Bill 109) to become law without a signature making Maryland the second state to have a food container foam ban on the books, but is the first one to take effect on July 1, 2020. Polystyrene (PS) is recyclable plastic #6. Linear polymers containing side groups as part of monomer structure do not qualify as branched polymers [3,12]. Polystyrene's Structure. At room temperature, the thermoplastic polymer is a solid but when heated above 100 °C it flows. Oriented polystyrene (OPS) is produced by stretching extruded PS film, improving visibility through the material by reducing haziness and increasing stiffness. [96] 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. Due to the low density of polystyrene foam, it is not economical to collect. It is easily dissolved by many aromatic hydrocarbon solvents and chlorinated solvents. Structure, properties, spectra, suppliers and links for: Styrene, Styrolene, phenylethene, vinylbenzene, 100-42-5, 82988-08-7. [67] In 2013, San Jose became reportedly the largest city in the country to ban polystyrene foam food containers. The American Chemistry Council, formerly known as the Chemical Manufacturers' Association, writes: Based on scientific tests over five decades, government safety agencies have determined that polystyrene is safe for use in foodservice products. [59] Juvenile rainbow trout exposed to polystyrene fragments have produced toxic effects by causing substantial histomorphometrical changes.[60]. [73], In March 2019, Maryland banned polystyrene foam food containers and became the first state in the country to pass a food container foam ban through the state legislature. Pure polystyrene has the following structure. Polystyrene is an aromatic polymer, naturally transparent, made up of monomer styrene. Under tensile stress, crazes (microcracks) are formed, which spread to the rubber particles. 1. If styrene-butane co-polymer has a high butylene content, styrene-butadiene rubber (SBR) is formed. When the material is heated above the glass transition point, the domains disintegrate, the cross-linking is temporarily suspended and the material can be processed like a thermoplastic.[55]. [91], From 1999 to 2002, a comprehensive review of the potential health risks associated with exposure to styrene was conducted by a 12-member international expert panel selected by the Harvard Center for Risk Assessment. It can have serious effects on the health of birds or marine animals that swallow significant quantities. This benzene ring makes styrene an aromatic compound. Structurally, it is a long hydrocarbon chain, with a phenyl group attached to every other carbon atom. [79], India and Taiwan also banned polystyrene-foam food-service ware before 2007. It is an inexpensive, transparent, rigid, easily molded polymer and possesses excellent electrical and moisture resistance. 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. This is a better picture of what the monomer styrene looks like: The model above is … Styrene is a certain organic chemical compound having the chemical formula C 8 H 8.Its chemical structure is made up of a vinyl group bonded onto a benzene ring. However, the middle block often does not consist of such depicted butane homo-polymer but of a styrene-butadiene co-polymer: SSSSSS­SSSSSSS­SSSSSSBBSBBSB­SBBBBSB­SSBBBSBSSSSSSS­SSSSSSS­SSSSSS. 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. for bifunctional structural units. HDPE is composed of macromolecules in which n ranges from 10,000 to … Linear polymers are generally more rigid. The Harvard study reported that styrene is naturally present in trace quantities in foods such as strawberries, beef, and spices, and is naturally produced in the processing of foods such as wine and cheese. [99], Because of the pervasive use of polystyrene, these serious health related issues remain topical. Styrene is the precursor to polystyrene and several copolymers. (C 8 H 8) n is a synthetic aromatic hydrocarbon polymer with chemical name Polystyrene. supervisors OK toughest ban on foam packaging in U.S", "The Throwaway Generation: 25 Billion Styrofoam Cups a Year", "Maryland Foam Packaging Ban, Energy Bills to Become Law", "Statement: Maryland becomes the second state to ban plastic foam containers", "Maryland's new laws: banning foam food containers, raising tobacco-buying age, reforming UMMS board", "Even Paper Bags Will Be Banned From N.J. Supermarkets", "China moves to end its 'ban' on PS food packaging", "Expanded polystyrene (kaylite): What are its impacts? In fact, hot foods and liquids begin a partial breakdown of the Styrofoam allowing certain contaminants to be absorbed into our bloodstream and tissues. From p. 312: (Analysis, as well as synthesis, have equally demonstrated, that styrol and the solid, glassy material, for which we suggest the name "meta styrol", possess the same percentage composition. Styrene is the precursor to polystyrene and several copolymers. Polymerization The process is similar to pulling apart th… 6. For polyethylene, arguably the simplest polymer, this is demonstrated by the following equation. Maine was the first state to officially get a foam food container ban onto the books. Without applied force, the rubber phase initially behaves like a filler. Polystyrene (PS) plastic is a thermoplastic that is naturally transparent and available both as a standard solid plastic and in the form of a rigid foam material. If polystyrene is properly incinerated at high temperatures (up to 1000 °C[86]) and with plenty of air[86] (14 m3/kg[citation needed]), the chemicals generated are water, carbon dioxide, and possibly small amounts of residual halogen-compounds from flame-retardants. Polystyrene (PS) / ˌ p ɒ l i ˈ s t aɪ r iː n / is a synthetic aromatic hydrocarbon polymer made from the monomer known as styrene. Polypropene, also known as polypropylene, is made up of monomer propene. [100], Like other organic compounds, polystyrene is flammable. PS can also be prepared by solution and suspension techniques. Detailed information and chemical structures are included on product pages. Extruded polystyrene is also permeable by water molecules and can not be considered a vapor barrier.[46]. Polystyrene's Structure. (C8H8)n is a synthetic aromatic hydrocarbon polymer with chemical name Polystyrene. The catalyst remains active during the whole process (for which the used chemicals must be of high purity). The length of the individual blocks can be adjusted by the ratio of catalyst to monomer. a polymer: Homopolymers are polymers made by joining together monomers of the same chemical composition or structure. Here you can see a model and a diagram of the styrene monomer. The size of the rubber sections, in turn, depends on the block length. FDA. Syndiotactic polystyrene (SPS) is a semicrystalline polymer synthesized from styrene monomer using a single-site catalyst such as metallocene. Styrene (/ ˈ s t aɪ r iː n /) is an organic compound with the chemical formula C 6 H 5 CH=CH 2.This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish.The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor. 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. The chain is then initiated when a peroxy radical combines with a styrene monomer, forming an active center on the end opposite the initiator. 3.3 Non-linear polymers5 In general, polystyrene is not accepted in curbside collection recycling programs and is not separated and recycled where it is accepted. Ordinary (homo-polymeric) polystyrene has an excellent property profile about transparency, surface quality and stiffness. Polymerization The solvation efficiency of the org-MMT with monomer depends not only on the nature of the organic group intercalated in the MMT and but also on the chemical structure of the monomer used(4). The styrene monomer (from which polystyrene is made) is a cancer suspect agent. At room temperature and pressure, styrene is a clear, colorless liquid.Other names for styrene can be styrol, vinylbenzene, phenylethene, or phenylethylene. The hydrogen bonds to the carbon in an alternating pattern via Van der Waals attractions (or the weak attraction of atoms and molecules of opposite charges). "[89][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.[90]. The chemical structure of polystyrene can be seen in Figure 1: Figure 1: Styrene monomer Polystyrene is produced by free radical vinyl polymerization, from the monomer styrene. STRUCTURE BASED NAME. Physical properties of polystyrene depend on the processing, molecular mass distribution and nature of additives. • Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Some benefits to OPS are that it is less expensive to produce than other clear plastics such as polypropylene (PP), (PET), and high-impact polystyrene (HIPS), and it is less hazy than HIPS or PP. Solid polystyrene is transparent, owing to these large, ring-shaped molecular groups, which prevent the polymer chains from packing into close, crystalline arrangements. Styrene-butadiene rubber thus consists of a rubber matrix with a polystyrene phase dispersed therein. ", "Styrene in the Crosshairs: Competing Standards Confuse Public, Regulators", "Foul Play Considered in Channel Tunnel Fire Inquiry", Take a Closer Look at Today’s Polystyrene Packaging, "Certification of SRM1960: Nominal 10 μm Diameter Polystyrene Spheres ("Space Beads")", https://en.wikipedia.org/w/index.php?title=Polystyrene&oldid=991310728, Wikipedia articles needing page number citations from November 2017, Wikipedia articles needing factual verification from September 2020, Articles lacking reliable references from October 2018, Chemicals that do not have a ChemSpider ID assigned, Articles containing unverified chemical infoboxes, Articles with unsourced statements from January 2016, Articles with unsourced statements from June 2015, Articles with unsourced statements from July 2013, Articles lacking reliable references from July 2013, Articles with unsourced statements from June 2011, Creative Commons Attribution-ShareAlike License, Soluble in benzene, carbon disulfide, chlorinated aliphatic hydrocarbons, chloroform, cyclohexanone, dioxane, ethyl acetate, ethylbenzene, MEK, NMP, THF, Depron, a thin insulation sheet also used for model building, This page was last edited on 29 November 2020, at 11:39. Polystyrene foams are produced using blowing agents that form bubbles and expand the foam. The energy of the propagating crack is then transferred to the rubber particles along its path. Rastra is made from EPS that is combined with cement to be used as an insulating amendment in the making of concrete foundations and walls. Some of the common examples of linear polymers are polyethylene, PVC, polystyrene, and polyamides. However, if the waste material goes through an initial compaction process, the material changes density from typically 30 kg/m3 to 330 kg/m3 and becomes a recyclable commodity of high value for producers of recycled plastic pellets. Your email address will not be published. This makes it the perfect choice for making floating boards. Discover monomers that may be used to synthesize custom polymers to meet the your specific needs. Polystyrene, Polyethenylbenzene, Lustrex®, Styron®, Vestyron®, Styrofoam®, Fome-Cor®, Luran®. Ordinary (homopolymeric) polystyrene has an excellent property profile about transparency, surface quality and stiffness. Butadiene is then added and after styrene again its polymerization. [74][75][76][77], In September 2020, the New Jersey state legislature voted to ban disposable foam food containers and cups made of polystyrene foam. Copolymers called ABS have similar properties and can be used at low temperatures, but they are opaque. The original impetus was to eliminate chlorofluorocarbons (CFC), which was a former component of foam. Polystyrene is classified according to DIN4102 as a "B3" product, meaning highly inflammable or "Easily Ignited." [52]:476 The material is stable (no further phase segregation occurs) because polybutadiene and polystyrene are chemically linked. Styrene-butane co-polymers include PS-I and SBC (see below), both co-polymers are impact resistant. Polymer Structure. Polystyrene food service packaging keeps the food fresh for a longer period of time and is less expensive than alternatives. However, compliance has been a problem and, in 2013, the Chinese plastics industry was lobbying for the ban's repeal.