Effect of stirring on the emulsion polymerization of styrene

Abstract

SynopsisThe purpose of this paper is to clarify the effect of stirring on the course of emulsion polymerization of, for example, styrene. It establishes the existence of an optimum range of stirring speed and three important factors which must be considered in carrying out emulsion polymerization. (1) Stirring significantly affects the course of reaction in the presence of an imperfectly purified nitrogen atmosphere. Consequently, the number of polymer particles produced and the polymerization rate per particle will be affected. (2) At higher stirring speeds, polymer particles coagulate and coalesce. At lower stirring speeds, the reaction rate is controlled by the monomer transport rate from monomer droplets to the aqueous phase. (3) Stirring contributes to the reduction of the number of micelles because emulsifier molecules are adsorbed onto the surfaces of monomer droplets finely dispersed by the stirring. At low emulsifier concentrations near the critical micelle concentration, this effect cannot be neglected.

Aspects of coagulation during emulsion polymerization of styrene and vinyl acetate

“…fects from the nucleation interval on the development of the particle size distribution. In contrast with Nomura et al 31 …”

“…In the first region the pulsion no longer contributes to the colloidal stability of the latex system. The only stabilization electrostatic repulsion between the latex particles 8e5c 5458 / 8E5C$$5458 07-14-98 12:23:16 polaa W: Poly Applied et al, 31 however, reported that at higher stirrer mechanism left is the steric hindrance. As a consespeeds, the particle number ( determined by quence, there is a resistance for particles for close TEM analysis ) decreases during ab initio emulapproach.…”

Role of micellar equilibria on modelling of batch emulsion polymerization reactors

“…It is worthwhile pointing out that the effect of particle coalescence has been neglected (i.e., p = 0), due to the low stirring speed and the large emulsifier concentration; this has been experimentally verified by Nomura et al 25 for the styrene polymerization. In the case of butadiene polymerization the emulsifier concentration was large in all the examined runs, so that also the homogeneous nucleation mechanism can be neglected (i.e., k , = 0).…”

Reaction kinetics of vinyl acetate emulsion polymerization

“…Harada et al= and Nomura et al [23][24][25] considered the transport of monomer-unit free radicals out of the latex particles into the aqueous phase and employed the Smith-Ewart recursion equation to calculate the average number of free radicals per particle for the emulsion polymerization of vinyl acetate. The desorption rate constant was correlated to several physical and kinetic parameters such as the diffusion coefficient of monomer-unit free radical in the latex particle and the particle size.…”