Production of polystyrene

A twin-screw extmder is used to reduce residual monomers from ca 50 to 0.6%, at 170°C and 3 kPa with a residence time of 2 min (94). In another design, a heated casing encloses the vented devolatilization chamber, which encloses a rotating shaft with specially designed blades (99,100). These continuously regenerate a large surface area to faciUtate the efficient vaporization of monomers. The devolatilization equipment used for the production of polystyrene and ABS is generally suitable for SAN production. 

Benzene is alkylated with ethylene to produce ethylbenzene, which is then dehydrogenated to styrene, the most important chemical iatermediate derived from benzene. Styrene is a raw material for the production of polystyrene and styrene copolymers such as ABS and SAN. Ethylbenzene accounted for nearly 52% of benzene consumption ia 1988. 

Fig. 6. U.S. production of polystyrene versus production year (103). A, Total B, straight C, impact (mbber modified) D, ABS.

World polystyrene production in 1997 was approximately 10 million tons. The demand is forecasted to reach 13 million tons by 2002. The 1997 U.S. production of polystyrene polymers and copolymers was approximately 6.6 billion pounds. ABS, SAN, and other styrene copolymers were approximately 3 billion pounds for the same year. 

The key to the successful production of polystyrene is the reaction. The ratio of materials to be used is a compromise of the literature values, as was discussed in the section on the scope. All the authors discussing suspension polymerization say the reaction should be allowed to go to completion. (Removing and recycling the unreacted styrene would be more expensive.) It will be assumed that this means 99.8% of the styrene is reacted, and that this can be accomplished by using an average of the temperatures and cycle times given in Table 2E-2. 

During 1930s, the commercial interest of polystyrene started due to its good electrical insulation characteristics. During the second world war, two companies, namely, I.G. Farben-industries (Germany) and Dow Chemical Company (USA) started the large scale production of polystyrene. 

Emulsion Polymerisation It is a very good process which is used for the preparation of polystyrene. Emulsion polymerisation which is mainly used in the production of polystyrene latex used in water-based surface coating. 

Thus the stage was set for the production of polystyrene. The First Steps (1930-1945)... 

The large demand for benzene is due to its use as a starting material in the production of polystyrene, acrylonitrile styrene butadiene rubber, nylons, polycarbonates and linear alkyl benzene detergent. All of these final chemical products that are suitable to form into consumer goods have multiple chemical transformations in various industrial processes to obtain them from benzene. Because the production of benzene does not involve a liquid adsorptive process on a zeolite, these processes are not described here but can be found in other sources. However, it is important to note that benzene is typically a large byproduct from an aromatics... 

Continuous solution polymerization is the most important method for the commercial production of polystyrene although suspension polymerization is also used [Moore, 1989]. 

Chloroethane is produced by the hydrochlorination of ethylene. It is used in the manufacture of tetraethyllead, as an industrial ethylating agent, as a blowing agent in the production of polystyrene foam and as a local anaesthetic. Occupational exposure occurs during the production of tetraethyllead, and industrial emissions have led to detectable levels of chloroethane in ambient air (lARC, 1991). 

Styrene and its derivatives can be polymerized by all possible propagation mechanisms. Free-radical polymerization, however, is the primary process for industrial production of polystyrene. Free-radical polymerization of styrene can be carried out without chemical initiators simply by heating the monomer.223,224 On heating, isomeric 1-phenyltetralins are formed in the Diels-Alder... 

Use the kinetic model in Appendix 13.1 to design a CSTR for the production of polystyrene. The entering feed is pure styrene. It is desired to produce 50% by weight of polystyrene with a number average molecular weight of 85,000. The feed flow rate is 25,000 kg/h. Determine the required operating temperature and reactor capacity (in mass units). 

A. Tanaka, H. Staudinger s research and the birth of the polymer industry in Germany. I. The foundation of industrial production of polystyrene and polyvinyl chloride plastics , Kagakushi Kenkyu, 1996,23,1-14, 147-166 [in Japanese],... 

Polystyrene A polymer of styrene, used primarily in the production of polystyrene foam for use in packaging. 

Cedap, (European Consortium of Plastic Applications), was established in 1963 in Monaco. Its main activity is the production of polystyrene sheet for food packaging. Cedap is a division of Siamp-Cedap. 

Figure 1.1 Early photograph of the can process for the commercial production of polystyrene. This simple process involved filling 10 gallon metal cans with styrene monomer, thermally polymerizing it in heated baths and then grinding the polystyrene cylinders that formed, (courtesy of Dow Chemical Company)...

Prior to 1941, Germany had a major technical and industrial lead over the USA, having already established an industrial styrene monomer production process, a styrene-butadiene elastomer process and a mass styrene polymerization process [6]. Figure 1.2 shows the polymerization vessels at I. G. Farben in 1940. Figure 1.3 shows a bank of polymerization kettles. The Germans began the first technical production of polystyrene in 1930 while the first production of polystyrene in the USA was some 8 years later by Dow in 1938. 

Figure 7.4 Multifunctional peroxides that have been evaluated for the fast production of polystyrene...

The synthesis and characterization of the hydrogenation product of polystyrene (PS), poly(cyclohexylethylene) (PCHE), have been the subject of persistent research efforts. The earliest published report on this material dates to 1929, with new work appearing steadily up to the present. The primary motivation for saturating the phenyl rings in polystyrene is the potential to improve the stability of polystyrene with respect to oxidative and radiation-induced degradation. It has now also been established that the hydrogenation of polystyrene leads to a substantial increase in the glass transition temperature (Tg). 

In Japan, the production of polystyrene (PS) is fairly high for example, 115 00001 were produced in 1999, involving one of the four major general-purpose type resins. It has been reported that some kinds of styrene oligomers, which are by-products of polymerization, remained in PS products [1]. In the Wingspread statement announced by Colborn et al. in 1996, it was reported that certain synthetic chemicals have endocrine-disrupting effects on humans or animals. Most of these chemicals are pesticides, but styrene dimers (SDs) and trimers (STs) are listed in this statement along with plasticizers and antioxidants [2]. 

Extensions of the early model employed mass balances across all components.i The model agreed well with experimental data for the production of polystyrene. However, as in most traditional models it was a particle number model, based on all particles being identical. These models helped analyze polymerization in terms of the number concentration of polymer particles containing actively polymerizing radicals of number, Ai(t). As a result, they contained no particle size... 

In depth studies in the degradation products of polystyrene and their involvement in inducing property changes has led some workers to conclude that lower molecular weight functions are more susceptible to oxidative attack. 

At high temperatures, [Ru(CH3)(Tp)(CO)(NCMe)] acts as catalyst for the production of polystyrene. The dependence of polystyrene molecular weight on benzene/cumene molar ratios suggests a radical polymerization mechanism. The polymerization of methyl methacrylate, in the presence of [Ru(CH3)(Tp)(CO)(NCMe)j with carbon tetrachloride or methyl dichloroacetate, has been observed at 90°C.31... 

In previous papers (4, 13, 14), we described the preparation of high impact products of polystyrene (PS) and poly (vinyl chloride) (PVC) by radi-... 

MAJOR USES Used in the production of polystyrene, resins, plastics, rubber, boats, ice cream, candy, paints, coatings, copolymers, styrenated phenols and oils. 

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