Polystyrene batch suspension process

Typical Formulations Used for the Batch Suspension Process for Polystyrene... 

ABB Lummus Global/BP Amoco Polystyrene, expandable Styrene One-step batch suspension process with high reactor productivity 1 1997... 

FIG. 23-23 Batch and continuous polymerizations, (a) Polyethylene in a tiihiilar flow reactor, up to 2 km long hy 6,4 cm ID, (h) Batch process for polystyrene, (c) Batch-continuous process for polystyrene, (d) Suspension (head) process for polyvinylchloride, (e) Emulsion process for polyvinylchloride, (Ray and Laurence, in Lapidus and Amundson, eds, Chemical Reactor Theory Review, Frentice-Hall, 1977. )... 

There are many different ways of making polystyrene using the suspension process. Most producers use a batch process, although there are no technical reasons why a continuous process could not work.10 For this study a batch... 

The second large-scale process was the batch mass suspension process. Monsanto did the pioneer work on this (41). In this process, prepolymerization is carried out in bulk and main polymerization in suspension the latter is taken to conversions of over 99%. In contrast to the continuous mass process, peroxide starters are used in order to achieve a high conversion at tolerable reaction times. Figure 3 shows a basic flow diagram of such a plant. A detailed discussion of advantages and disadvantages of the two processes can be found in R. Bishop s monograph published in 1971 (42), and it is continued in a paper by Simon and Chappelear in 1979 (43). It was a decisive factor for the economic success of impact polystyrene that these processes had been completely developed and mastered in theory and practice. 

At present all commercial polystyrene (with average molecular weights between 100,000 and 400,000) is manufactured by radical polymerization, which yields atactic polymers.476 Peroxides and azo compounds are commonly used initiators. The suspension process (usually as a batch process in water at 80-140°C) produces a product with relatively high residual monomer content.223 More important is the continuous solution process (usually in ethylbenzene solvent at 90-180°C), which yields high-purity product. Styrene can be copolymerized with numerous other monomers.477 One of these copolymers, the styrene-divinylbenzene copolymer produced by free-radical polymerization, has a crosslinked stucture and is used in... 

Today, HIPS is produced by two basic variants the batch process and the continuous process. Pre-polymerization, i.e. the polymerization phase up to completion of phase inversion, is identical in the two process variants. After completion of the pre-polymerization, the polymerization is continued in suspension in the batch process and in solution in the continuous process. The batch process is, therefore, also referred to as the bulk suspension process and the continuous variant as the solution process. The continuous process is a refinement of the original I.G. Farben process for standard polystyrene, which The Dow Chemical Company has adapted to the needs of rubber-containing styrene solutions. A number of modifications are now practiced. 

The commercial manufacture of polystyrene was batch mode through the 1930s and 1940s, with a gradual transition to continuous bulk polymerization beginning in the 1950s. Suspension polymerization was a common early polystyrene production process, where a single reactor produced a polymer slurry that had to be separated from the water and dried. This process was ideal for free radical... 

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