Emulsification of a viscous monomer mix: Particle size and size distribution

Abstract

A non-Newtonian mixture of monomers, their copolymer and pigment was dispersed into water with emulsifier by a rotor-stator homogenizer (Brinkmann Polytron). Volume median diameters d,, of the droplets, measured by Coulter Counter or optical microscopy, were typically 4-20 pm; d,(, was about inversely proportional to monomer fraction (0.2 to 1 .O), or to rotor speed (4000 to 1 1000 rpm). Increasing the emulsifier from 0.1 % to 3% roughly halved d5,,; volume fraction of organic phase had little effect. Turbulent dispersion theory (Calabrese et al., 1986a,b), adapted to non-Newtonian drops, represented the data but with different numerical constants. A high geometric standard deviation, around I .7 but increasing slightly as monomer fraction decreased, may be due to non-uniform turbulence and to the complexity of breakup at high viscosity.Un melange non newtonien de monomkres, de leur copolymkre et d'un pigment a etC disperse dans I'eau avec un emulsifiant par un homogkneiseur de type rotor-stator (Brinkmann Polytron). Les diamktres moyens de volume d,,, des gouttelettes, mesurkes par Coulter Counter ou microscopie optique, sont typiquement de 4-20 pm; d,, est inversenient proportionnel a la fraction de monomkre (0,2 a 1,O) ou i la vitesse du rotor (4 000 a 1 1 000 t r h i n ) . L'augmentation de I'Cmulsifiant de 0,l a 3% reduit de moitie d5"; la fraction volumique de la phase organique a peu d'effet. La thCorie de dispersion turbulente (Calabrese et al., 1986a,b), adaptke aux gouttelettes non newtoniennes, reprisente les donnees mais avec des constantes numiriques differentes. L'Ccart type gComCtrique ClevC, d'environ 1,7 mais augmentant legkrement avec la diminution de la fraction de monomkre, pourrait Ctre d~ a la turbulence non uniforme et i la complexit6 de la rupture des viscosites elevies.

An Updated Review on Suspension Polymerization

“…However, the range of viscosity they used was very low (up to 10 Pa‚s). In studying a non-Newtonian mixture of monomers, their copolymer, and pigment dispersed into water with emulsifier, Chaffey et al (1991) described the drop's rheology with the Herschel-Bulkley law (a power law model). However, their analysis of the dispersion phenomena was performed semiempirically using dimensionless-group correlations.…”