Slurry Polymerization Mode

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... 

Fig. 3 The media milling process is shown in a schematic representation. The milling chamber charged with polymeric media is the active component of the mill. The mill can be operated in a batch or a recirculation mode. A crude slurry consisting of drug, water, and stabilizer is fed into the milling chamber and processed into a nanocrystalline dispersion. The typical residence time required to generate a nanometersized dispersion with a mean diameter <200 nm is 30-60 min. (From Liversidge, E.M. Liversidge, G.G. Cooper, E.R. Eur. J. Pharm. Sd. 2003,18, 113-120).

The earliest polymerization processes were either batch mode or semibatch. The semibatch method was used for products, where the two monomers differed greatly in reactivity, as in Union Carbide s early Dynel, acrylonitrile-vinyl chloride, process. Bulk, solution, and emulsion polymerization processes have also been developed for acrylonitrile and its copolymers. However, in recent years nearly every major acrylic fiber producer has used a continuous aqueous suspension process, employing a redox catalyst, followed by a series of steps, which includes slurry filtration and polymer drying. 

Until about the mid-1990s, polyethylene research laboratories usually possessed several polymerization systems depending on the size of the research program. It was common procedure that each investigator had a dedicated polymerization reactor for individual research. These singlebatch reactors were about 1-5 liter in capacity and ran in either a slurry or solution mode. Often these individual reactors would be used to carry out a designed experiment in which two or three process variables would be investigated at two levels each. This required 4-8 separate experiments which would take about one week to carry out in the case of three variables at two levels, or 8 individual experiments. 

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