Commodity plastics polystyrene

Growth in the demand for styrene is growing worldwide at about 4 to 5% annually. However, the major use for the styrene monomer is for use in the commodity plastic polystyrene. This commodity is declining in amount relative to the other commodity plastics, such as polypropylene. 

Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mosdy in single apphcation niches, unlike workhorse resins such as PVC, phenoHc, urea—melamine, and polyurethane. More expensive engineering resins have a very limited role in the building materials sector except where specific value-added properties for a premium are justified. Except for the potential role of recycled engineering plastics in certain appHcations, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The apphcation content of each resin type is noted in Table 2. Comparative prices can be seen in Table 5. The most dynamic growth among important sector resins has been seen with phenoHc, acryUc, polyurethane, LLDPE/LDPE, PVC, and polystyrene. 

We can divide commodity plastics into two classes excellent and moderate insulators. Polymers that have negligible polar character, typically those containing only carbon-carbon and carbon-hydrogen bonds, fall into the first class. This group includes polyethylene, polypropylene, and polystyrene. Polymers made from polar monomers are typically modest insulators, due to the interaction of their dipoles with electrical fields. We can further divide moderate insulators into those that have dipoles that involve backbone atoms, such as polyvinyl chloride and polyamides, and those with polar bonds remote from the backbone, such as poly(methyl methacrylate) and poly(vinyl acetate). Dipoles involving backbone atoms are less susceptible to alignment with an electrical field than those remote from the backbone. 

Thermoplastic Polymers. Most thermoplastic polymers are used in high-volume, widely recognized applications, so they are often referred to as commodity plastics. (We will elaborate upon the distinction between a polymer and a plastic in Chapter 7, but for now we simply note that a plastic is a polymer that contains other additives and is usually identified by a variety of commercial trade names. There are numerous databases, both in books [1] and on the Internet [2], that can be used to identify the primary polymer components of most plastics. With a few notable exceptions, we will refer to most polymers by their generic chemical name.) The most common commodity thermoplastics are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS). These thermoplastics all have in common the general repeat unit -(CHX-CH2)-, where -X is -H for PE, -CH3 for PP, -Cl for PVC, and a benzene ring for PS. When we discuss polymerization reactions in Chapter 3, we will see that all of these thermoplastics can be produced by the same type of reaction. 

Polystyrene was commercialized by I. G. Farben in 1931 and it has long been used as a commodity plastic. Although polystyrene is endowed with excellent properties not found in other commodity plastics such as polyolefins, its amorphous nature (relatively low heat and solvent resistance) limits its use in some application areas. 

Commodity and engineering polymers. On the basis of end use and economic considerations, polymers can be divided into two major classes commodity plastics and engineering polymers. Commodity plastics are characterized by high volume and low cost. They are used frequently in the form of disposable items such as packaging film, but also find application in durable goods. Commodity plastics comprise principally of four major thermoplastic polymers polystyrene, polyethylene, polypropylene, and poly(vinyl chloride). 

Thermoplastics may be further subdivided into two broad categories on the basis of their cost and suitable end uses. Commodity plastics are typified by high volume production, good properties, and low resin cost. The four major commodity plastics are polyethylene, polypropylene, poly(vinyl chloride), and polystyrene. Their adequate properties and low cost have led to the extensive use of these plastics in packaging applications where they are very competitive with paper, steel, and glass. They are also used for some less demanding applications as components of durable goods (Table 22.1). 

In the end Monsanto didn t share that optimism. It decided to drop the program in late 1998. Michael Berezo, the Monsanto executive who had headed the Biopol program before the shutdown, told me in early 1999 that these materials cost about 10 times as much as comparably performing petroleum-based (and not biodegradable) commodity plastics, such as polyesters, some polyolefin, and polystyrenes. Berezo didn t consider biodegradability a big, positive selling aspect. ... 

Plastics are not, as many people believe, new materials. Their origin can be traced to 1847 when Shonbein produced the first thermoplastic resin, celluloid, by reaction of cellulose with nitric acid. However, the general acceptance and commercialization of plastics began during the Second World War when natural polymers, such as natural rubber, were in short supply. Thus, polystyrene was developed in 1937, low density polyethylene in 1941, whereas other commodity plastics such as high density polyethylene and polypropylene were introduced in 1957. 

Thermoplastics, in particular the commodity plastics, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and polystyrene (PS), are the most commonly used in packaging (over 90% of packaging is thermoplastics, followed by a small amount of thermosets, composites, rubber and thermoplastic elastomers (TPE). 

Despite its origin form the nature, PLA s good stiffness and strength has enabled it to compete with other existing chemically based commodity plastics. Previous study on the mechanical properties of neat PLA by Jacobsen et al. [1] showed that PLA has great potential to be a substitute polymer for petroleum based plastics. The respective values of mechanical properties of PLA [2] with comparison of other petroleum based plastics e.g. polypropylene (PP) [3], polystyrene (PS) [4], high density polyethylene (HOPE) [5], polyamide (PA6) [6] shown in Fig. 11.2. 

Polystyrene (PS) is a commodity plastic manufactured on a large scale. It is considered to be nonpolar. The applications of PS are limited in high-performance engineering products due to its brittleness. It is used as light coverings or in the transparent parts of electrical appliances. To overcome brittleness, PS has been extensively modified, and its copolymers and blends represent the most versatile class of polymeric materials [13]. Its properties are listed in Table 2.3. 

Omitting the construction and demolition debris from the calculations, the composition (by volume this time) is as follows paper and paperboard 50%, plastics 14%, metals 12%, glass 4%, organics 6%, and miscellaneous 14%. All plastic packaging (post-consumer, industrial, commercial, and institutional) represented about 8% of the overall refuse. It is a reasonable assumption that the composition of plastics discarded in landfills is a reflection of the quantities produced for packaging applications the commodity plastics polyethylene, polypropylene, polystyrene, and poly(vinyl chloride) should be well represented (see Ethylene POLYMERS PROPYLENE Polymers (PP) Styrene Polymers Vinyl Chloride Polymers). 

In compact-disc (and DVD) manufacturing, the upper face is usually made of an inexpensive polycarbonate or made of a copolycarbonate. The face is covered by a very thin metal layer (usually Al) which reflects diode-laser light. The metallic layer must be protected by a plastic layer (this constitutes the lower face). It is made of polystyrene (or other commodity plastic). The annual production of PC around the world was about 3500 thousand tons in 2007 (5). There are more than ten industries around the world which produce PC. For a long time polycarbonate market needs were satisfied by only two manufacturers, i.e. the GE plastics (an american company renamed SABIC Innovative Plastics in 2007) and Bayer (a German firm). Later other manufacturers have joined them - Dow Chemical, Samyang, Asahi Kasei and Teijin. The most popular PC trade names are LEXAN , CALIBER, SINVETTM, MAKROLONTM. Popular names for PC-PET blends are listed elsewhere (16). 

The pendant methylene group in PP is replaced by a chlorine atom in polyvinyl chloride (PVC), by a benzene ring in polystyrene (PS) and by a hydrogen atom in polyethylene (PE). The pendant group significantly affects the properties of the polymer, and consequently the properties of PP are very different from other commodity plastics such as PE, PVC and PS (Section 4). 

Plastic materials have become basic and indispensable in our life. To protect against contamination and conserve them, food products are distributed in different plastic packages bags, bottles, boxes, etc. that contain all kinds of edible products liquid (water, milk, cold beverages) or solid (fruit, meat, fish, frozen foods, etc.). The group of commercial plastics, also termed commodity plastics, consists of the most used polymers in terms of volume and number of applications. They are mainly polystyrene (PS), polypropylene (PP), high-and low-density polyethylene (HDPE, LDPE), polyethylene terephthalate (PET) and, in lower proportion, polycarbonate (PC) [71. 

Polypropylene is the fastest growing of the top four commodity thermoplastics used in the plastics industry. Polypropylene is sometimes preferred over other commodity plastics because it has a lower density (adds less weight to the car). PP has been replacing some of the uses of polystyrene, polyvinyl chloride, and ABS resin. New PP capacity is growing so rapidly in Asia and the Middle East that by the next decade the United States will switch from being a net exporter of PP to becoming a net importer. 

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