Styrenic plastics styrene acrylonitrile

Many cellular plastics that have not reached significant commercial use have been introduced or their manufacture described in Hterature. Examples of such polymers are chlorinated or chlorosulfonated polyethylene, a copolymer of vinyUdene fluoride and hexafluoropropylene, polyamides (4), polytetrafluoroethylene (5), styrene—acrylonitrile copolymers (6,7), polyimides (8), and ethylene—propylene copolymers (9). 

Styrene [100-42-5] (phenylethene, viaylben2ene, phenylethylene, styrol, cinnamene), CgH5CH=CH2, is the simplest and by far the most important member of a series of aromatic monomers. Also known commercially as styrene monomer (SM), styrene is produced in large quantities for polymerization. It is a versatile monomer extensively used for the manufacture of plastics, including crystalline polystyrene, mbber-modifted impact polystyrene, expandable polystyrene, acrylonitrile—butadiene—styrene copolymer (ABS), styrene—acrylonitrile resins (SAN), styrene—butadiene latex, styrene—butadiene mbber (qv) (SBR), and unsaturated polyester resins (see Acrylonithile polya rs Styrene plastics). 

Not only ate ABS polymers useful engineering plastics, but some of the high mbber compositions are excellent impact modifiers for poly(vinyl chloride) (PVC). Styrene—acrylonitrile-grafted butadiene mbbers have been used as modifiers for PVC since 1957 (87). 

ABS plastic, a polymer consisting of polybutadiene spheroids is dispersed in a continuous phase of poly(styrene—acrylonitrile). The chromic acid attacks the polybutadiene at a much higher rate than the continuous phase. This gives an excellent microroughened surface with superior metal-to-plastic bond strength. A typical recommended formulation consists of 20 vol % sulfuric acid, 420 g/L chromic acid, and 0.1—1.0% of a fluorocarbon wetting agent. The plastic is treated with this formulation for 6—10 min at 60—65°C. 

In addition to polystyrene and high-impact polystyrene there are other important styrene-based plastics. Most important of these is ABS, with a global capacity of about 5 X 10 t.p.a. and production of about 3 X 10 t.p.a. The styrenic PPO materials reviewed in Chapter 21 have capaeity and production figures about one-tenth those for ABS. Data for the more specialised styrene-acrylonitrile copolymers are difficult to obtain but consumption estimates for Western Europe in the early 1990s were a little over 60000 t.p.a. 

Some typical properties of styrene-acrylonitrile plastics, referred to in many countries as SAN, are compared with those of other styrene-based plastics in Table 16.7. 

Styrene-acrylonitrile plastics are used on a smaller scale in a variety of areas as may be seen from Table 16.11. Individual applications were discussed in Section 16.7. 

Coran and Patel [33] selected a series of TPEs based on different rubbers and thermoplastics. Three types of rubbers EPDM, ethylene vinyl acetate (EVA), and nitrile (NBR) were selected and the plastics include PP, PS, styrene acrylonitrile (SAN), and PA. It was shown that the ultimate mechanical properties such as stress at break, elongation, and the elastic recovery of these dynamically cured blends increased with the similarity of the rubber and plastic in respect to the critical surface tension for wetting and with the crystallinity of the plastic phase. Critical chain length of the rubber molecule, crystallinity of the hard phase (plastic), and the surface energy are a few of the parameters used in the analysis. Better results are obtained with a crystalline plastic material when the entanglement molecular length of the... 

Acrylonitrile is mainly used to produce acrylic fibers, resins, and elastomers. Copolymers of acrylonitrile with butadiene and styrene are the ABS resins and those with styrene are the styrene-acrylonitrile resins SAN that are important plastics. The 1998 U.S. production of acrylonitrile was approximately 3.1 billion pounds. Most of the production was used for ABS resins and acrylic and modacrylic fibers. Acrylonitrile is also a precursor for acrylic acid (by hydrolysis) and for adiponitrile (by an electrodimerization). 

SAN (styrene acrylonitrile) Polyvinyl chloride Plasticized Unplasticized Polyvinylidene chloride Styrene copolymer (SMA) Crystal Impact... 

Odor and taste Polystyrene, styrene-acrylonitrile, polyethylene, acrylic, ABS, polysulfone, EVA, polyphenylene oxide, and many other TPs are examples of satisfactorily odor-free. FDA approvals are available for many of these plastics. Food packaging and refrigerating conditions will also eliminate certain plastics. There are TPs and melamine as well as urea compounds that are suitable for this service. 

The primary use of acrylonitrile is as the raw material for the manufacture of acrylic and modacrylic fibers. Other Major uses include the production of plastics (acrylonitrile-butadiene- styrene (ABS) and styrene-acrylonitrile (SAN), nitrile rubbers, nitrile barrier resins, adiponitrile and acrylamide (EPA 1984). 

Most plastics e.g. polyolefins and polystyrenes and their derivatives such as ABS (acrylonitrile-butadiene-styrene) and SAN (styrene-acrylonitrile) are supplied by the manufacturers in ready-to-use form with most of the above-mentioned stabilizers or simply need to be additionally stabilized with other additives, e.g. antistatic agents and HALS stabilizers, as required. On the other hand, in the case of other materials (e.g. PVC) it is the end user who adds the additives, pigments or preparations. This is normally done on fluid or high-speed mixers, although in the past gravity mixers or tumble mixers were also used. The mixture is then homogenized on mixing rolls, kneaders, planetary extruders or twin-screw kneaders and further processed. 

ISO 4894-1 1997 Plastics - Styrene/acrylonitrile (SAN) moulding and extrusion materials -Part 1 Designation system and basis for specifications ISO 4894-2 1995 Plastics - Styrene/acrylonitrile (SAN) moulding and extrusion materials -Part 2 Preparation of test specimens and determination of properties ISO 19220 2004 Plastics piping systems for soil and waste discharge (low and high temperature) inside buildings - Styrene copolymer blends (SAN PVC)... 

Uses. Plastics and synthetic rubber are the major uses for styrene. They account for the exponential growth from a few million pounds per year in 1938 to more than 8 billion pounds today. The numerous plastics include polystyrene, styrenated polyesters, acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), and styrene-butadiene (SB). Styrene-butadiene rubber (SBR) was a landmark chemical achievement when it was comrner-cialized during World War II. The styrene derivatives are found everywhere—in food-grade film, coys, construction pipe, foam, boats, latex paints, tires, luggage, and furniture. 

In Table 8.4 we see that most butadiene is polymerized either by itself or with styrene or acrylonitrile. The most important synthetic elastomer is styrene-butadiene rubber (SBR). SBR, along with polybutadiene, has its biggest market in automobile tires. Specialty elastomers are polychloroprene and nitrile rubber, and an important plastic is acrylonitrile/butadiene/styrene (ABS) terpolymer. Butadiene is made into adiponitrile, which is converted into hexamethylenediamine (HMDA), on of the monomers for nylon. 

The most important commercial processes for polyacrylonitrile (XLIII) are solution and suspension polymerizations. Almost all the products containing acrylonitrile are copolymers. Styrene-acrylonitrile (SAN) copolymers are useful as plastics (Sec. 6-8a). 

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. 

Abbreviations for plastics ABS, acrylonitrile-butadiene-styrene CPVC, chlorinated poly vinyl chloride ECTFE, ethylene-chlorotrifluoroethylene ETFE, ethylene-tetrafluoroethylene PB, polybutylene PE, polyethylene PEEK, poly ether ether ketone PFA, perfluoroalkoxy copolymer POP, poly phenylene oxide PP, polypropylene PVC, polyvinyl chloride PVDC, poly vinylidene chloride PVDF, poly vinylidene fluoride. 

Figure 5.99 Relationship of glass fiber content with (a) tensile strength and (b) flexural modulus for styrene acrylonitrile (SAN) and polypropylene (PP). Reprinted, by permission, from G. Lubin, Handbook of Fiberglass and Advanced Plastics Composites, p. 130. Copyright 1969 by Van Nostrand Reinhold.

M.H. Tusim and T.W. Rhoads, Plasticizers for expandable styrene-acrylonitrile resin, US Patent 5 071606, assigned to The Dow Chemical Company (Midland, MI), December 10,1991. 

Fig. 1. US total sales and captive use of selected thermoplastic resins by major market for 2001. Major market volumes are derived from plastic resins sales and captive use data as compiled by VERIS Consulting, LLC and reported by the American Plastics Council s Plastic Industry Producers Statistics Group. Selected thermoplastics are low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, nylon, polyvinyl chloride, thermoplastic polyester, engineering resins, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, other styrenics, polystyrene, and styrene butadiene latexes. (Data from ref. 25.)...

Toughened polystyrene and other related plastics like acrylonitrile-butadiene-styrene can be extruded to produce opaque, coloured sheet for thermoforming, and as profiles and pipe. Techniques are available by which good surface finish may be obtained, but under typical conditions the extruded surfaces will be matt or satin . 

Of the styrene copolymers used for food packaging the styrene-acrylonitrile copolymer known as SAN still needs to be mentioned. SAN copolymers possess better mechanical properties and better resistance to oils and aroma compounds than PS. Copolymers with acrylonitrile fractions of 20-35 % find uses as household and camping dishes. Copolymers with a higher acrylonitrile content (> 60%) have earned particular importance as barrier plastics. With an increasing acrylonitrile fraction, the gas permeability decreases sharply. 

Acrylic fibers are by far the major end use for acrylonitrile. They find use primarily in fabrics for clothing, furniture, draperies, and carpets. The second largest consumer of acrylonitrile is acrylonitrile-butadiene-styrene (ABS) and styrene acrylonitrile (SAN) resins. ABS is useful in industrial and construction applications, and the superior clarity of SAN makes it useful in plastic lenses, windows, and transparent household items. 

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