Anionic Polymerization of Styrene in a Tubular Reactor

Abstract

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.