Mechanism of emulsion polymerization of vinylidene chloride. III. Effects of stirring rate on kinetics

Abstract

The effect of stirring speed on the rate of the persulfate‐catalyzed polymerization of vinylidene chloride has been determined. It was found that the first‐stage rate decreases with increasing stirring speed, that the second‐stage rate increases with increasing stirring speed, and that the rate of the third stage is independent of stirring speed. These results, as well as those of an earlier paper, may be explained in the following manner. The second stage slow‐down results from monomer starvation, caused by slow diffusion from coalesced droplets. Recovery is caused by transfer of monomer at the time of collision between a polymer particle and a monomer droplet. These collisions are allowed when the repulsive forces between monomer droplet and polymer particle are reduced because of surfactant deficiency.

Nanoparticle formation by highly diffusion-controlled emulsion polymerisation

“…At a low stirring speed, the rate of monomer transport (R a ) to polymerising particles is diffusion controlled (Evans et al, 1961;Nomura et al, 1972). This has been associated with a * Corresponding author.…”

Diffusion‐Controlled Particle Growth and its Effects on Nucleation in Stirred Emulsion Polymerisation Reactors

“…Early literature indicates a significant influence of the degree of agitation on the behaviour of emulsion polymerisations. [2] In practice, there has been found a ''safe bound'' within which the rate of polymerisation (R p ) and number of particles (N p ) are independent of the stirring speed. [3] At a high stirring speed, particles may coagulate to give a smaller N p as well as a lower R p .…”

“…[3] At a low stirring speed, the rate of polymerisation is diffusion controlled. [2][3][4][5] This has been associated with a formation of a larger number of particles. [6][7][8] The effects of impeller speed and/or type on the rate of copolymerisation, molecular weights, [4,9] and particle size distribution [10] have been also reported.…”

Agitation effects in the semicontinuous emulsion polymerization of styrene and butyl acrylate

“…Because polymerization is highly exothermic, an efficient agitation is required to ensure a uniform temperature throughout the reactor and to maximize the heat-removal rate. For vinylidene chloride, Evans et al 5 observed different effects of the agitation for the three stages in which emulsion polymerization can be divided. 2,3 Most of the works reported in the literature on the effect of agitation on emulsion polymerization focused on batch reactors.…”