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.

Ionic Polymerization

“…In ideal plug flow reactors under steady-state conditions, polymers with the same characteristics of the MWD as in batch reactors are built -the time axis is transformed to the length axis of the plug flow reactor [74,75], and for fast initiation the MWD is a Poisson distribution. For laminar plug flow reactors [75,76] some broadening of the distribution is observed, depending on ½M 0 =½I 0 and conversion.…”

“…In ideal plug flow reactors under steady-state conditions, polymers with the same characteristics of the MWD as in batch reactors are built -the time axis is transformed to the length axis of the plug flow reactor [74,75], and for fast initiation the MWD is a Poisson distribution. For laminar plug flow reactors [75,76] some broadening of the distribution is observed, depending on ½M 0 =½I 0 and conversion. The long-term stability of laminar flow tubular reactors is questioned [76], because of the possibility of very long chains growing near the reactor walls, where the residence time approaches infinity, if radial diffusion of the monomer occurs from the inner tube to the walls.…”

“…Some are using recirculated loop reactors [148][149][150][151] or single-pass tubular reactors [75,152,153], which may be segmented [154]. A spray tower [155] has a similar residence time distribution, but heat removal is by a countercurrent nitrogen stream.…”

Molecular weight distribution in low-density polyethylene polymerization; impact of scission mechanisms in the case of a tubular reactor

“…In case the ow in a tubular reactor is laminar, there are potential di culties in operation due to the gradients in reactant properties in radial direction. A detailed discussion on the possible problems in operation of tubular process can be found in Nauman (1987), Kim (1996) and Kim and Nauman (1999). However, in tubular reactors for ldPE polymerization mostly turbulent ow prevails, so that most segregation di culties are avoided.…”

Thiol-ene/hyperbranched polymer hybrid thin films: Cure behavior and gas barrier properties

“…Compared with dendrimers obtained from multistep syntheses [7,8], HBPs are more advantageous as they can be easily synthesized through one-step polymerization processes [9,10]. Because of their highly functionalized globular structures, HBPs exhibit different properties from those of linear polymers of the same molar mass, such as less entanglement in the solid state [11], high solubility in various solvents, and low melt viscosity [12][13][14]. Terminal groups of HBPs have a great influence on their physical properties such as glass transition temperature (T g ) [15], relaxation process [16], viscosity [17], and solubility [18].…”