Dispersion polymerization typical recipe

Some typical dispersion polymerization recipes and the electron micrograph of the uniform polymeric particles with Recipe I are given in Table 5 and Fig. 10, respectively. As seen in Table 5, the alcohols or alcohol-water mixtures are usually utilized as the dispersion media for the dispersion polymerization of apolar monomers. In order to achieve the monodispersity in the final product, a costabilizer can be used together with a primary steric stabilizer, which is usually in the polymeric form as in... 

Table 5 Typical Dispersion Polymerization Recipes Providing Uniform Latex Particles...

The physical picture of emulsion polymerization is based on the original qualitative picture of Harkins [1947] and the quantitative treatment of Smith and Ewart [1948] with subsequent contributions by other workers [Blackley, 1975 Casey et al., 1990 Gao and Penlidis, 2002 Gardon, 1977 Gilbert, 1995, 2003 Hawkett et al., 1977 Piirma, 1982 Poehlein, 1986 Ugelstad and Hansen, 1976]. Table 4-1 shows a typical recipe for an emulsion polymerization [Vandenberg and Hulse, 1948]. This formulation, one of the early ones employed for the production of styrene-1,3-butadiene rubber (trade name GR-S), is typical of all emulsion polymerization systems. The main components are the monomer(s), dispersing medium, emulsifier, and water-soluble initiator. The dispersing medium is the liquid, usually water,... 

The minimum requirements for a dispersion polymerization are monomer, solvent/nonsolvent, initiator, and steric stabilizer. The monomer must be soluble in the reaction mixture and its polymer, insoluble. The monomers used in systems of commercial interest are methyl methacrylate, vinyl chloride, vinyli-dene chloride, vinyl esters, hydroxyl alkyl acrylates. A typical recipe for dispersion polymerization is shown in Table 9. 

Typical Recipes for Dispersion Polymerizations of e-Caprolactone and Lactide 649... 

In the case of suspension copolymerization of acrylonitrile-styrene mixtures of 10-40 wt% acrylonitrile and 40-90 wt% styrene are polymerized in H2O in the presence of inorganic dispersing agents according to the typical recipe presented in Table 4 to produce transparent copolymer beads containing >90% 100-400- x mesh particles. 

A typical emulsion polymerization recipe includes specific proportions of the added ingredients, e.g. (in wt%) monomer, 100 water, 150 initiator, 0.5 surfactant, 5. Because the monomer has low water solubility, it is clear that there will be two separate phases referred to as the monomer phase and the aqueous phase. The aqueous phase, containing the surfactant in the form of micelles, can be considered as consisting of two phases, the micellar phase and the true aqueous phase. The emulsifier helps disperse the monomer in the aqueous phase with droplets in the order of a few micrometers in size. The hydrophobic interior of the micelles contains solubilized monomer, which is apportioned by diffusion out of the emulsified monomer droplets and through the aqueous phase. 

Other Components. The smaller the particle size, at a given phase ratio, the more difficult it is to ensure colloidal stability (cf Fig. 5). This means that for aqueous heterophase polymerizations in the order suspension < microsuspension < emulsion < miniemulsion < microemulsion, the stabilizer concentration increases. Contrary to the simple polymerization of st5Tene in water, polymerization recipes for industrially important polymer dispersions comprise up to six monomers, frequently more than two emulsifiers, more than one initiating system, and a few other aids like biocides, defoaming agents, plasticizers for supporting film formation (39). The monomer-to-water ratio is adjusted in such a way that a solid content results typically between 40 and 60% or even higher. The amoimts of surfactants and initiator (mainly peroxodisulfate) are typically between 0.5 and 2% (w/w) relative to the monomers and 0.5% (w/w) relative to water, respectively. 

Very little has been reported about the use of spectroscopic methods for monitoring and control of other polymerization systems. Lenzi et al. [191] reported that the NIR spectra collected in a dispersive instrument with a transflectance probe may contain very useful information about the structure of core-shell polystyrene beads produced through simultaneous semibatch emulsion/suspension polymerizations. Lenzi et al. [192] developed a polymerization technique that combines recipes of typical emulsion and suspension polymerizations to produce core-shell polymer beads. More interesting, the appearance of the core-shell structure always led to qualitatively different NIR spectra that could not have been obtained with polymer suspensions, polymer emulsions, or mixtures of polymer suspensions and emulsions. As described by Lenzi et al. [191], different spectral peaks could be detected in the wavelength region constrained between 1700 and 1900nm when the core-shell structure developed. 

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