TABLE OF CONTENTS A polymer emulsion is principally a dispersion of organic polymer particles in water [8, 20, 30]. Indeed a latex normally comprises a dispersion of fine particles in an aqueous solution, i.e., water. Latexes (polymer emulsions) are commonly formed by an emulsion polymerisation process [1, 2, 6, 9, 20, 31, 32]. This procedure involves the addition and reaction of a designated monomer (i.e., vinylacetate for vinylacetate latexes), a co-monomer where necessary (vinylester, versatic acid), a surfactant, initiator and water.
Latexes can possess a rubbery consistency and hence be elastomeric in nature like SBR, natural rubber, polyacrylonitrile and polychloroprene [8, 10]. Alternatively they can be thermoplastic, hence the structure becomes more elastic and pliable when exposed to chemicals or heat, i.e., polystyrenes, polyvinylacetates, copolymers of styrene and vinylacetates.
Depending on the surfactants utilised during the polymerisation reactions the latex polymers can be positively (cationic), negatively (anionic) charged or possess no charge whatsoever (non-ionic) [8, 9, 20]. Non-ionic polymer particles are generally the most suitable for use with Portland cements [8, 20].
Generally a number of emulsion polymerisation methods can be used to manufacture these dispersions [8, 33, 34]:
Semi-continuous polymerisation,
Batch polymerisation,
Continuous polymerisation.
The monomer is added in certain proportions over a specific timescale in the semi-continuous method. Whilst, the entire monomer concentration is added in a single addition during the batch manufacturing process. Typically 20 tons of polymer emulsion will be produced by...
