United States polystyrene production

Polystyrene is the fourth largest thermoplastic polymer made in the United States by production volume. It... 

Styrene was first isolated in 1831 by Bonastre from the resin of the amber tree. In 1839, E. Simon, who also first described the pol5mier, gave the monomer its name. Around 1925, the development of an industrial production process for polystyrene (the molecular structure shown in Figure 4.1) began this work achieved success in Germany in 1930. In the United States, polystyrene was first produced on a commercial scale in 1938. 

Cellofoam Polystyrene foam board United States Mineral Products Co. 

Benzene was prepared from coal tar by August W von Hofmann m 1845 Coal tar remained the primary source for the industrial production of benzene for many years until petroleum based technologies became competitive about 1950 Current production IS about 6 million tons per year m the United States A substantial portion of this ben zene is converted to styrene for use m the preparation of polystyrene plastics and films... 

The annual production of styrene in the United States is approximately 1 2 X 10 lb with about 65% of this output used to prepare polystyrene plastics and films Styrofoam coffee cups are made from polystyrene Polystyrene can also be produced m a form that IS very strong and impact resistant and is used widely m luggage television and radio cabinets and furniture... 

Capacity. Estimated ABS capacity worldwide in 1989 is given in Table 3. Accurate ABS capacity figures are difficult to obtain because significant production capabiHty is considered "swing" and can be used to manufacture polystyrene or SAN as weU as ABS. The United States has the largest ABS nameplate production capacity of any country at 867 x 10 tons accounting for approximately 25% of the world s capacity. Three producers... 

Table 6 shows the sales estimates for principal film and sheet products for the year 1990 (14). Low density polyethylene films dominate the market in volume, followed by polystyrene and the vinyls. High density polyethylene, poly(ethylene terephthalate), and polypropylene are close in market share and complete the primary products. A number of specialty resins are used to produce 25,000—100,000 t of film or sheet, and then there are a large number of high priced, high performance materials that serve niche markets. The original clear film product, ceUophane, has faUen to about 25,000 t in the United States, with only one domestic producer. Table 7 Hsts some of the principal film and sheet material manufacturers in the United States.

More than 500 million pounds of poly(vinyl acetate) (PVAc), poly(vinylidene chloride), and their copolymers and polymers derived from them are produced annually in the United States. PVAc does not have sufficient strength for producing the types of products obtained from polyethylene, polystyrene, and poly(vinyl chloride) since it is noncrystalline and has a Tg of only 28°C. However, poly(vinyl acetate) (XLI) and its copolymers find uses as... 

Copolymerization allows the synthesis of an almost unlimited number of different products by variations in the nature and relative amounts of the two monomer units in the copolymer product. A prime example of the versatility of the copolymerization process is the case of polystyrene. More than 11 billion pounds per year of polystyrene products are produced annually in the United States. Only about one-third of the total is styrene homopolymer. Polystyrene is a brittle plastic with low impact strength and low solvent resistance (Sec. 3-14b). Copolymerization as well as blending greatly increase the usefulness of polystyrene. Styrene copolymers and blends of copolymers are useful not only as plastics but also as elastomers. Thus copolymerization of styrene with acrylonitrile leads to increased impact and solvent resistance, while copolymerization with 1,3-butadiene leads to elastomeric properties. Combinations of styrene, acrylonitrile, and 1,3-butadiene improve all three properties simultaneously. This and other technological applications of copolymerization are discussed further in Sec. 6-8. 

Most polystyrene products are not homopolystyrene since the latter is relatively brittle with low impact and solvent resistance (Secs. 3-14b, 6-la). Various combinations of copolymerization and blending are used to improve the properties of polystyrene [Moore, 1989]. Copolymerization of styrene with 1,3-butadiene imparts sufficient flexibility to yield elastomeric products [styrene-1,3-butadiene rubbers (SBR)]. Most SBR rubbers (trade names Buna, GR-S, Philprene) are about 25% styrene-75% 1,3-butadiene copolymer produced by emulsion polymerization some are produced by anionic polymerization. About 2 billion pounds per year are produced in the United States. SBR is similar to natural rubber in tensile strength, has somewhat better ozone resistance and weatherability but has poorer resilience and greater heat buildup. SBR can be blended with oil (referred to as oil-extended SBR) to lower raw material costs without excessive loss of physical properties. SBR is also blended with other polymers to combine properties. The major use for SBR is in tires. Other uses include belting, hose, molded and extruded goods, flooring, shoe soles, coated fabrics, and electrical insulation. 

Butadiene is used primarily in the production of synthetic rubbers, including styrene-butadiene rubber (SBR), polybutadiene nibber (BR), styrene-butadiene latex (SBL), chloroprene rubber (CR) and nitrile rubber (NR). Important plastics containing butadiene as a monomeric component are shock-resistant polystyrene, a two-phase system consisting of polystyrene and polybutadiene ABS polymers consisting of acrylonitrile, butadiene and styrene and a copolymer of methyl methacrylate, butadiene and styrene (MBS), which is used as a modifier for poly(vinyl chloride). It is also used as an intermediate in the production of chloroprene, adiponitrile and other basic petrochemicals. The worldwide use pattern for butadiene in 1981 was as follows (%) SBR + SBL, 56 BR, 22 CR, 6 NR, 4 ABS, 4 hexamethylenediamine, 4 other, 4. The use pattern for butadiene in the United States in 1995 was (%) SBR, 31 BR, 24 SBL, 13 CR, 4 ABS, 5 NR, 2 adiponitrile, 12 and other, 9 (Anon., 1996b). 

Decabromodiphenyl ether continues to be a popular fire-retardant additive for polyamide 6, its cost, high bromine content, and good thermal stability make it an attractive product. In Europe and the United States, most of its applications have been replaced by brominated polystyrene in order to address environmental issues. Brominated polystyrene is less expensive than the other polymeric fire retardants and has very good thermal stability. Moreover, it contributes to good electrical tracking index. On the other hand, it has lower efficacy as a fire retardant. 

United States alone, 5 x 109 kg of plastic resins (typically used in packaging and transportation) are produced every year. Disposable goods and packing material represent about one-third of the total plastic production and have the largest environmental impact. More than 90% of the plastic material in municipal waste consists of polyethylene, polyvinyl chloride, and polystyrene, which are all resistant to biodegradation (see Table 9.1). 

Over a period of many years polymeric materials have gradually replaced metals in many applications. Among the five leading thermoplastics low and high density polyethylene, polyvinyl chloride, polypropylene, and polystyrene polyethylene is the largest volume plastic in the world. Polyethylene was initially made in the United States in 1943. In 1997, the estimated combined worldwide production of both low and high-density polyethylene was 1.230 x 1010 kg (2.712 x 1010 lb) [10]. Low density polyethylene is produced at pressures of 1030 to 3450 bar (1020 to 3400 atm) whereas high density polyethylene is produced at pressures of 103 to 345 bar (102 to 340 atm) [11]. 

Projections for 1995 given in parentheses, Kirk-Othmer [34]. In the same year it was projected that a total of 669,000 tonnes of polystyrene foam products would be produced in the United States. 

Figure 6.22 United States styrene and polystyrene production histories. (Data courtesy of CMAI.)...

In 1991, the production of methyl methacrylate was 1.84 million tons per year [41]. The United States, Western Europe, and Japan produced 0.66, 0.54, and 0.46 million tons per year, respectively [42], The cost for methyl methacrylate in 1991 was 0.62/lb [43]. Most acrylics start with methyl methacrylate monomer (MMA). Methyl methacrylate is used in the production of poly(methyl methacrylate) and in copolymers to improve the impact resistance of other vinyl polymers [44], Poly(methyl methacrylate) is a colorless transparent plastic with a higher softening point, better impact strength, and better weatherability than polystyrene [45]. 

World consumers used 215 billion lb of the five most commonly used plastics in 1996.119 This included 41% polyethylene, 23% polyvinyl chloride, 21% polypropylene, 11% polystyrene, and 4% styrene-acrylonitrile copolymers. The world production of polyethylene tereph-thalate in 1996 was 9.8 billion lb. The United States plastics use in 1995 was 71.2 billion lb, of which 27% was used... 

Plastics make up only about 8 percent of the volume in the average landfill but represent a huge investment of energy and raw materials. Most plastics produced from petroleum materials by polymerization of monomers such as ethylene or vinyl chloride are thermoplastic materials and can be cleaned, melted, and re-formed. Thermosetting plastics can also be cut into pieces that are mixed with other plastics or used as fillers. High-density polyethylene (HDPE) and polyethylene terephthalate (PETE) are the most widely reused plastic materials, but polyvinyl chloride (PVC), polypropylene, and polystyrene account for 5 percent of the recycled plastics. In 2001 80 million pounds (36 milfion kilograms) of plastics were recycled in the United States. Recycled plastic materials are used in the production of bottles, fabrics, flowerpots, furniture, plastic lumber, injection molded crates, and automobile parts. 

More than 99 percent of the ethylbenzene made is used for a single purpose—the production of styrene. Styrene is a very important industrial chemical, ranking seventeenth among all chemicals produced in the United States in 2004. It is used to make a number of important and popular polymers, the best known of which may he polystyrene. Much smaller amounts of ethylbenzene are used in solvents or as additives to a variety of products. Some products that contain ethylbenzene include synthetic rubber, gasoline and other fuels, paints and varnishes, inks, carpet glues, tobacco products, and insecticides. 

Polystyrene dust and powder formed during production can be a mild irritant to the eyes, skin, and respiratory system. But even for workers in the field, the risk is regarded as being very low. A more serious problem posed by the compound is the risk it poses for the environment. About half of all the polystyrene produced in the United States is used for packaging and one-time use purposes. That is, someone uses the product and then throws it away. Since polystyrene does not readily decompose, it tends to accumulate in landfills and dumps. Some environmentalists point out that large volumes of discarded polystyrene contribute significantly to the nation s solid waste disposal problems. Industry spokespersons, however, point out that polystyrene accounts for less than one percent of all solid wastes. In any case, a number of industries and companies have attempted to reduce the amount of polystyrene used in their products in order to... 

The manufacture of polystyrene and styrene copolymers has grown at a rapid rate during the last decade. In 1946, the production of polystyrene in the United States amounted to 60 million lb in 1956, polystyrene produc-tiiHi reached 390 million lb. Further development of new polystjirmie grades, of modified polyst3rrenes, and of new copolymers will certainly result in a cimtinuing expansion this field. 

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