For high-volume products, continuous processes are generally preferred over batch processes since they typically give more consistent quality at lower cost. Despite this, most commercial anionic polymerizations are batch because of a variety of stability issues. This paper explores the feasibility of a tubular process for high-molecular-weight polystyrene with low polydispersity. Experimental results show number-average chain lengths of 600−2600 with polydispersities of 1.05−1.42. Apparent steady states were achieved. A comprehensive process model based on available transport and kinetic properties gave reasonable predictions. A single adjustable parameter improved the model to the point that it is adequate for design purposes. This adjustable parameter accounts for the initial deactivation of a n-butyllithium initiator due to the trace contaminates in the raw materials. Scale-up to industrial-scale production appears feasible, although long-term stability must be explored.

The feasibility of manufacturing narrow polydispersity polymers in continuous flow systems is explored. The method of moments is applied to ideal and more realistic kinetic schemes in a variety of reactor types. In most cases, polydispersities approaching those obtained in batch can also be achieved in continuous reactors, but the long-term stability of a tubular reactor with species-dependent, radial diffusion remains in doubt.