Polystyrene and its Copolymers

This is a hard fairly brittle material. Chemically it is unaffected by acids, alkalies, lower alcohols and most paraffinic hydrocarbons. It is attacked by certain foodstuffs, e.g., orange peel oil. It is a reasonably good barrier to gas but a poor one to water vapour. 

The brittleness of polystyrene can be overcome by incorporation of a synthetic rubber, such as polybutadiene or styrene-butadiene rubber in amounts up to 10%. The increase in impact strength and flexibility thus acquired is accompanied by some loss in clarity, so that only opaque or translucent grades of toughened polystyrene are available. This does not however, limit its uses in food packaging. 

Polystyrene is also available in an expanded (cellular) form and as such is used extensively in the fabrication of vending machine drinking cups. 

The physical properties of polystyrene are improved by copolymerisation with acrylonitrile or acrylonitrile and butadiene. Styrene - acrylonitrile (SAN) is tough and transparent and is used in the manufacture of measuring jugs, orange and lemon squeezers and food homogenisers. 

Acrylonitrile - butadiene - styrene (ABS) can be manufactured to have a range of properties, depending on the ratio of the monomers present and the order in which the monomers are polymerised. 

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Table 9.4 shows the uses of styrene. These are dominated by polymer chemistry and involve polystyrene and its copolymers. We will study these in detail later, but the primaiy uses of polystyrene are in various molded articles such as toys, bottles, and jars, and foam for insulation and cushioning. Styrene manufacture is a large business. With a production of 11.4 billion lb and a price of 30C/lb styrene has a commercial value of approximately 3.4 billion. 

Systems in which a polyolefin is the binder have attracted world-wide attention. These include the polyethylene—phenolic microsphere 74,115>, polyethylene or polypropylene—glass microsphere114116), polyethylene or polybutylene—PVC microsphere (containing isobutane)52), and polyethylene/vinyl acetate copolymer—glass microsphere11 systems. Syntactic foams have been made from polystyrene (and its copolymers with chlorostyrene or polychlorostyrene) and microspheres made from polyethylene or polypropylene46115 and foams from styrene/acrylonitrile 1171... 

The uses of styrene are dominated by polymer chemistry and involve polystyrene and its copolymers as used in various molded articles such as toys, bottles, and jars and foam for insulation and cushioning. 

Seven families of thermoplastics exceed a billion pounds per year in the United States polyethylenes, polypropylene, PVC, polystyrene and its copolymers, polyethylene terephthalate, acrylonitrile-butadiene-styrene (ABS) and nylon (Table 15.2). 

Polystyrene and its Copolymers. Polystyrene (Table 15.7) is made by continuous bulk polymerization, initiated by peroxides and... 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

Radiation-induced Degradation.—There have been several reports on radiation effects in polymers,288 including single crystals,287 fluoropolymers,288 polyamides,289 polysiloxanes,270 polyethylene and its copolymers,271 polypropylene,272 polyolefins,273 polystyrene and its copolymers,274 poly(vinyl chloride) and related polymers,275 rubbers,278 polysulphones and other sulphur-containing polymers,277 polycarbonate,278 nylon,279 poly(vinylpyridines),280 and wool.281... 

Phenolics are the most widely used antioxidants in plastics and are added to polyethylene and polystyrene and its copolymers. They may form coloured degradation quinine products on oxidation. The most widely used phenolic is butylated hydroxytoluene (BHT), which has an lUPAC name 2,6-di-t-butyl-4-methylphenol. BHT is added to many polymers including those used for food... 

Organophosphites are secondary antioxidants which reduce hydroperoxides to alcohols. They inhibit the discolouration reaction experienced by phenolics. Tris-nonyl phenyl phosphite (TNPP) is the most commonly used. The disadvantage of phosphates is their high hygroscopicity. Thioesters act as secondary antioxidants by destroying hydroperoxides to form stable sulphur derivatives. In addition, thioesters impart high heat stability to polyolefins, polystyrene and its copolymers. The m or disadvantage of thioesters is their unpleasant odour which is transferred to the host polymer. 

Sulfonation reactions of polystyrene and its copolymers with divinyl benzene are carried out commercially to prepare ion exchange resins. Partial sulfonations of polystyrenes are achieved in the presence of ethers. When more than 50% of the aromatic rings are sulfonated, the polymers become water soluble. At lesser amounts of sulfonation (25-50%), the polymers are solvent soluble. ... 

Discuss chloromethylation reactions of polystyrene and its copolymers, showing all chemical reactions. 

Typical examples of polymer production in CSTRs include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR) and polychloroprene in CSTR trains polystyrene and its copolymers PVC and PVAC (and their copolymers) and LDPE. 

Styrenic Polymers Stabilization of polystyrene and its copolymers is necessary for articles expected to be exposed to solar radiation or indoor fluorescent lighting. Because of the signiflcant role played by thermal oxidation products in the effect of these sources on the polymers, thermal stabilization at the processing stage is required to reduce their sensitivity to light. The use of a phenolic antioxidant was shown to increase the retention of mechanical properties and. 

Figure 6. Arrhenius curves for polystyrene phosphorescence intensity in polystyrene and its copolymers containing keto or naphthalene groups [8].

Polystyrene and its copolymers account for about 10 percent of the domestic resin market. In its unmodified state, polystyrene is a hard, crystal-clear thermoplastic with relatively poor impact strength. Styrene is one of only a few vinyl monomers that can be polymerized by free radical, cationic, anionic, and Ziegler-Natta processes. 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

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... 

Polystyrene and its divinylbenzene cross-linked copolymer have been most widely exploited as the polymer support for anchoring metal complexes. A large variety of ligands containing N, P or S have been anchored on the polystyrene-divinylbenzene matrix either by the bromination-lithiation pathway or by direct interaction of the ligand with C1-, Br- or CN-methylated polystyrene-divinyl-benzene network [14] (Fig. 7). 

The following plain example might demonstrate the usefulness of the e° data. In benzene (e° = 0.32) polystyrene samples are eluted from a silica column, whereas polymethylmethacrylates and its copolymers are not. In THF (0.57) even PMMA homopolymers leave the column. Hence, THF is strong enough to prevent PMMA from adsorption. In chloroform (0.40) random copolymers with no more than 50%... 

Of great importance are the ethylene derivatives with aromatic substituents. Styrene (vinylbenzene) is one of the monomers produced industrially in large volume. Polystyrene and styrene copolymers still belong to the important representatives of modern plastics and rubbers. Styrene can be polymerized by any of the known procedures. It has suitable physical properties, and therefore it is one of the most frequently studied monomers. It also... 

This chapter discusses the dynamic mechanical properties of polystyrene, styrene copolymers, rubber-modified polystyrene and rubber-modified styrene copolymers. In polystyrene, the experimental relaxation spectrum and its probable molecular origins are reviewed further the effects on the relaxations caused by polymer structure (e.g. tacticity, molecular weight, substituents and crosslinking) and additives (e.g. plasticizers, antioxidants, UV stabilizers, flame retardants and colorants) are assessed. The main relaxation behaviour of styrene copolymers is presented and some of the effects of random copolymerization on secondary mechanical relaxation processes are illustrated on styrene-co-acrylonitrile and styrene-co-methacrylic acid. Finally, in rubber-modified polystyrene and styrene copolymers, it is shown how dynamic mechanical spectroscopy can help in the characterization of rubber phase morphology through the analysis of its main relaxation loss peak. 

Linear polystyrene can be functionalized by various methods . The functional group capacity in these polymers diould not be too high otherwise, steric complications may arise. Poly(ethylene ycol) has been found to be most suitable for liquid-phase synthesis. This linear polyether and the block copolymers with functional groups at defined distances are chemically stable and soluble in a large number of solvents including water and can be precipitated selectively. Partially hydrolyzed poly(vinylpyrrolidone) and its copolymers with vinyl acetate were successfully applied in peptide synthesis. Poly(acrylic acid), poly(vinyl alcdiol), and poly-(ethylenimine) are less suitable for the sequential type synthesis because of the... 

Commerically available samples of biaxially oriented polystyrene and SMA copolymer sheet material, having a thickness of 0.0381cm, were used in this investigation. It is generally recognized that crystallization under stress can enhance the tensile properties of a semi-crystalline polymer through a special arrangement of the crystalline portion ( 23). Therefore, the physical properties of the styrene-maleic anhydride copolymers chosen were compared to those of polystyrene produced in the same manner and are shown in Table I (24). 

It is instructive to calculate the key properties of specific polymers by using the correlation scheme developed in this book, to complement the earlier chapters where individual properties were calculated for large sets of polymers. Polystyrene, and random copolymers of styrene and oxytrimethylene, will be used as examples. Only the correlations which provide the preferred embodiment of our work will be used. In previous chapters, information provided by available group contributions and by related experimental data were incorporated in calculationss of "best estimates" of some properties. In this chapter, the properties will be calculated by using the new correlations consistently to estimate all parameters in intermediate steps of the calculations. Some values predicted below therefore differ from results listed in previous chapters. The steps involved in calculations of the properties will be listed. See earlier chapters for comparisons of the results with experimental data and with results of calculations using group contributions. 

U.S. Pat, Nos. 6,122,877 [107] and 6,682,814 [108] (both by Andersen Corporation) disclose a cellulosic fiber-polymeric composite comprising 45-70% of thermoplastic polymers such as PVC, polyethylene and its copolymers, polystyrene, polyacrylate, polyester and their mixtures, and 30-65% of wood fiber, such as sawdust. 

Type II rhamnogalacturonan is present in wine as a dimer (dRG-II-B). It may be isolated by adsorption chromatography on a polystyrene and divinylbenzene copolymer resin column (Pellerin et al., 1997). The average RG-II concentrations in white wines are between 20 and 60 mg/1, while those of red wines range from 100 to 160 mg/1. 

Polyvinyl chloride (PVC), which belongs to the family of vinyl polymers, and its copolymers vjith vinylidene chloride (PVDC), polystyrene (PS) and its copolymers, polyvinyl acetate (PVA), polyvinyl alcohol (PVAL), ethylene copolymers with vinyl alcohol (CEVA) are also employed in anticorrosion films [3,18,20,22-24]. 

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