Polycarbonates production

Fig. 4. Schematic of a hemodialyzer. The design of a dialyzer is close to that of a sheU and tube heat exchanger. Blood enters through an inlet manifold, is distributed to a parallel bundle of fibers, and exits into a coUection manifold. Dialysate flows countercurrent in an external chamber the blood and dialysate are separated from the fibers by a polyurethane potting material. Housings are typically prepared from acrylate or polycarbonate. Production volume is...

We routinely manufacture polycarbonate products by injection molding, blow molding, extrusion, and thermoforming. Injection molding is the most common processing technique. 

The field of metal-catalyzed copolymerization of oxetanes and C02 will continue to flourish, due not only to the versatility of the reaction but also to the aliphatic polycarbonate products being important components of thermoplastic elastomers that, in turn, have huge potential in medical applications such as sutures, drug-delivery systems, body, and dental implants, and tissue engineering. The exploration of other oxetane monomers (Figure 8.17) such as 3,3-dimethyloxetane and 3-methoxymethyl-3-methyloxetane, will surely provide a multitude of applications... 

Polycarbonates are amorphous polymers with excellent handling properties. Their spectrum of applications ranges from baby bottles to compact discs. Most of the polycarbonate produced is generated by the polycondensation of bisphenol A with phosgene in a biphasic system (sodium hydroxide/dichloromethane). The solution of the polycarbonate product in dichloromethane is washed with water to remove the by-product NaCl. However, in this washing process some 20 g L 1 of the dichloromethane ends up dissolved in the aqueous phase. The dichloromethane must also be removed from the polycarbonate, which is not easy. This means that the polycarbonate will invariably contain some chlorinated impurities, which adversely affects the properties of the polymer. 

Fukuoka, S., Tojo, M., Hachiya, H., Aminaka, M., and Hasegawa, K. 2007. Green and sustainable chemistry in practice Development and industrialization of a novel process for polycarbonate production from CO2 without using phosgene. Polymer Journal, 39 91-114. 

Morgan, S.E. Davis, G. Gijzen, E. Lemmen, T. The performance of sulfonate salt-containing polycarbonate products in flammability testing. ANTEC Soc. Plastics Eng. 1994, 3, 2840-2845. 

Fukuoka, S. Kawamura, M. Komiya, K. Tojo, M. Hachiya, H. Hasegawa, K. Aminaka, M. Okamoto, H. Fukawa, L Konno, S. A novel non-phosgene polycarbonate production process using by-product CO2 as starting material. Green Chem. 2003, 5 (5), 497-507. 

Various books on green or sustainable chemistry have discussed these aspects [2-15]. Many review papers have discussed general [15-24] or more specific aspects of green/sustainable chemistry and engineering such as monitoring strategies [25], microwaves in green and sustainable chemistry [26], polycarbonate production as... 

SCH Schilt, M.A. van, Wering, R.M., Meerendonk, W.J. van, Kemmere, M.F., Kenrentjes, J.T.F., Kleiner, M., Sadowski, G., and Loos, Th.W.de, High-pressnre phase behavior of the system PCHC-CHO-CO2 for the development of a solvent-free alternative toward polycarbonate production, Ind. Eng. Chem. Res., 44, 3363, 2005. 

Generic MACT Acetal Resins, Hydrogen Fluoride, Polycarbonates Production, Acrybc/Modacrylic Fibers 06/29/02... 

However, for AA and BB systems, like those shown in Table 7.1, stoichiometric imbalance can occur, with serious consequences for the polymerization. The molar ratio of the two types of functional end-groups (A and B) that are available for polymerization is determined by the initial molar ratio of the two monomers in a batch reactor, and by any monomers or oligomers that might escape from the reacting mixture during the polymerization. Note that escape of volatile monomers with the resulting influence on the ratio of functional groups is a serious practical problem for some industrial polymerizations that use volatile monomers (e.g., HMD in nylon 6,6 production and diphenyl carbonate in polycarbonate production). 

Bittner G, Yang CZ, Stoner MA. Estrogenic chemicals often leach from BPA-free plastic products that are replacements for BPA-containing polycarbonate products. Environ Health 2014 13 41. 

The excellent properties of the aromatic polycarbonates, particularly those based on 2,2-bis(4-hydroxyphenyl)propane (bisphenol A, or BPA), subsequently led to significant research into these materials by many organizations and a rush to develop commercial products. To date, the unique and commercially valuable properties of BPA polycarbonate have not been offset by any other commercially feasible aromatic diol. Hence, the commercial foundation for polycarbonate production has since been based on BPA-PC, although some copolymers with BPA-PC and other diols are also produced commercially. 

These linear polymers, in various molecular weights and with various monofunctional phenol end groups, dominate commercial polycarbonate production and sales. However, these products do not meet all requirements, particularly for extrusion and extrusion blow-molding applications where there is a need for polycarbonates that provide nonnewtonian, shear-dependent, viscoelastic flow properties. These desirable flow... 

Global polycarbonates production volume in 2006 approximately 2,9 million tons ... 

Figure 6-28. With the touch of a button, interior windows can change from clear to translucent, using liquid-crystal TP polyester film. This window consists of a two-layer laminated GE Lexan sheet to protect an inner polyester film. This polycarbonate product is strong and mar and UV resistant. The film is able to switch electrically between a highly translucent state providing privacy, glare control, and shading to a clear state for good visibility.

The production of 2,2-bis(4 -hydroxyphenyl)propane (commonly referred toby the trivial name bisphenol A) is described in Section 16.3.1.1). It may be noted that high-purity bisphenol A (namely m.p. 154—157°C) is used for the preparation of polycarbonates. Less pure material (such as is commonly used in the manufacture of epoxy resins) results in a polycarbonate with poor colour and physical properties. Bisphenol A is the preferred dihydroxy compound for polycarbonate production on the grounds of availability and all-round balance of properties of the resulting polymer. 

The solventless reaction in the presence of diallq ltin(iv) complexes led to a conversion of 42% with 78% selectivity to diphenyl carbonate. Starting from phenyl acetate, total conversion was obtained at 220 "C with higher selectivity to diphenyl carbonate (95%). Transesterification with higher alcohols was also examined, giving better conversion due to higher nucleophilicity compared to phenol. However, a steric effect was evidenced as fert-butanol was unreactive. Transesterification of ethylene carbonate (l,3-dioxolan-2-one) with methanol to dimethyl carbonate was also reported early. " Today, both transesterifications with methanol and phenol are integrated into the value chain of bisphenol-A polycarbonate production and commercialised by Asahi Kasei Corporation (Scheme 21.12). ... 

Darensbourg DJ, Lewis SJ, Rodgers JL, Yarbrough JC (2003) Carbon dioxide/epoxide coupling reactions utilizing Lewis base adducts of zinc halides as catalysts. Cyclic carbonate versus polycarbonate production. Inorg Chem 42 581-589... 

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