Commercial polystyrene

Initially various rubbery butadiene and styrene-butadiene block polymers were screened as impact-modifying agents for polystyrene. Commercial polystyrene and various rubbers were blended by dissolving the polymers in benzene and by subsequently precipitating them with isopropyl alcohol. The solid polymer blends were dried and molded into test bars. Laboratory and commercial polybutadiene and polystyrene were used in several combinations with the block polymer prepared in our laboratory. 

I. G. Farbenindustrie in Germany implemented such a concept to produce polystyrene commercially in the 1930s. Two CSTRs in parallel followed by a plug flow reactor were used in their process. During World War II, Union Carbide applied for a patent (US Patent 2496653, 1950) for a continuous polystyrene process. Their process consisted of three cascade CSTR reactors followed by a plug flow reactor. The temperature in the three CSTR reactors is 100, 115-120 and 140 °C, respectively. The conversion at the outflow of the third CSTR reactor is around 85 %. The temperature in the plug flow reactor is between 210 and 215 °C. The final conversion at the plug flow reactor was claimed to be 97 %. 

Figure 2. Transmission electron micrographs of six polybutadiene/polystyrene sequential IPN s and related materials, the polybutadiene portion stained with osmium tetroxide. Upper left high-impact polystyrene, commerciaL Upper right a similar composition made quiescently. Middle left semi-I IPN, PB (only) crosslinked. Middle right semi-II IPN, PS (only) crosslinked. Lower left full IPN, both polymers crosslinked. Lower right full IPN, PB with higher crosslink level. (Reproduce from ref. 5. Copyright 1976 American Chemical Society.)...

Epoxide (5), used in Chapter 6, is made from readily available styrene (6)— the monomer of polystyrene. Commercially available /wera-chloroperbenzoic acid (MCPBA) (7) is often used for such epoxidations. 

Dow also became interested in the production of polystyrene and in addition to its cellulosic and vinylidene chloride projects, also supported a project on polystyrene. One of the polymer pioneers, who was responsible for the commercialization of polystyrene at Dow, was Raymond Boyer. Dow produced polystyrene commercially in the US in 1935. Both IG Farbenindustrie and Dow used the Berthelot synthesis for the production of the styrene monomer. 

Syndiotactic polystyrene commercialized Styrene-ethylene copolymers Nanocomposites... 

Styrene—acrylonitrile (SAN) copolymers [9003-54-7] have superior properties to polystyrene in the areas of toughness, rigidity, and chemical and thermal resistance (2), and, consequendy, many commercial appHcations for them have developed. These optically clear materials containing between 15 and 35% AN can be readily processed by extmsion and injection mol ding, but they lack real impact resistance. 

AUoys of ceUulose with up to 50% of synthetic polymers (polyethylene, poly(vinyl chloride), polystyrene, polytetrafluoroethylene) have also been made, but have never found commercial appUcations. In fact, any material that can survive the chemistry of the viscose process and can be obtained in particle sizes of less than 5 p.m can be aUoyed with viscose. 

Commercial Construction. The same attributes desirable on residential constmction appHcations hold for commercial constmction as weU but insulation quaHty, permanence, moisture insensitivity, and resistance to free2e—thaw cycling in the presence of water are of greater significance. For this reason ceUular plastics have greater appHcation here. Both polystyrene and polyurethane foams are highly desirable roof insulations in commercial as in residential constmction. 

Other Polymers. Besides polycarbonates, poly(methyl methacrylate)s, cycfic polyolefins, and uv-curable cross-linked polymers, a host of other polymers have been examined for their suitabiUty as substrate materials for optical data storage, preferably compact disks, in the last years. These polymers have not gained commercial importance polystyrene (PS), poly(vinyl chloride) (PVC), cellulose acetobutyrate (CAB), bis(diallylpolycarbonate) (BDPC), poly(ethylene terephthalate) (PET), styrene—acrylonitrile copolymers (SAN), poly(vinyl acetate) (PVAC), and for substrates with high resistance to heat softening, polysulfones (PSU) and polyimides (PI). 

Initiators (1) and (2) have 10-h half-life tempeiatuies of 237°C and 201°C, respectively. It has been reported that, unlike organic peroxides and ahphatic azo compounds, carbon—carbon initiators (1) and (2) undergo endothermic decompositions (62). These carbon—carbon initiators are useful commercially as fire-retardant synergists in fire-resistant expandable polystyrenes (63). 

Foamed plastics (qv) were developed in Europe and the United States in the mid-to-late 1930s. In the mid-1940s, extmded foamed polystyrene (XEPS) was produced commercially, foUowed by polyurethanes and expanded (molded) polystyrene (EPS) which were manufactured from beads (1,2). In response to the requirement for more fire-resistant ceUular plastics, polyisocyanurate foams and modified urethanes containing additives were developed in the late 1960s urea—formaldehyde, phenoHc, and other foams were also used in Europe at this time. 

Fig. 2. Glass-transition temperature, T, for two commercially available, miscible blend systems (a) poly(phenylene oxide) (PPO) and polystyrene (PS) (42) ...

In the eady 1920s, experimentation with urea—formaldehyde resins [9011-05-6] in Germany (4) and Austria (5,6) led to the discovery that these resins might be cast into beautiful clear transparent sheets, and it was proposed that this new synthetic material might serve as an organic glass (5,6). In fact, an experimental product called PoUopas was introduced, but lack of sufficient water resistance prevented commercialization. Melamine—formaldehyde resin [9003-08-1] does have better water resistance but the market for synthetic glass was taken over by new thermoplastic materials such as polystyrene and poly(methyl methacrylate) (see Methacrylic polya rs Styrene plastics). 

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). 

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. 

Commercial styrene is used almost entirely for the manufacture of polymers. Polystyrene accounts for 64% of the worldwide demand for styrene. The rest is for manufacture of copolymers ABS, 9% SB latex, 7% UPR, 5% SBR, 4% others, 11%. 

Divinylbenzene. This is a specialty monomer used primarily to make cross-linked polystyrene resins. Pure divinylbenzene (DVB) monomer is highly reactive polymericaHy and is impractical to produce and store. Commercial DVB monomer (76—79) is generally manufactured and suppHed as mixtures of m- and -divinylbenzenes and ethylvinylbenzenes. DVB products are designated by commercial grades in accordance with the divinylbenzene content. Physical properties of DVB-22 and DVB-55 are shown in Table 10. Typical analyses of DVB-22 and DVB-55 are shown in Table 11. Divinylbenzene [1321 -74-0] is readily polymerized to give britde insoluble polymers even at ambient temperatures. The product is heavily inhibited with TBC and sulfur to minimize polymerization and oxidation. 

Polystyrene [9003-53-6] (PS), the parent of the styrene plastics family, is a high molecular weight linear polymer which, for commercial uses, consists of - 1000 styrene units. Its chemical formula (1), where n = - 1000, tells htde of its properties. 

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