Environmentally-Friendly Acrylates-Based Polymer Latices - Advanced Materials for Agriculture, Food and Environmental Safety - page 157

that the polymerization rate and monomer conversion increased with the
increase of emulsii er concentration, initiator concentration, and reaction
temperature.
J.I. Amalvy [78] investigated the ef ect of SLS in the synthesis of carbox-
ylic acrylic latexes of MMA, EA and methacylic acid (MAA) by emulsion
polymerization method. It was found that the surfactant concentration
had an important ef ect on the i nal properties of the latexes. Depending
on the i nal use of latex, an optimal range of surfactant concentration was
found for which the particle size, water uptake and mechanical properties
are appropriate.
Urretabizkaia and Asua [79] studied the ef ect of reaction parameters,
such as feed l ow rate, surfactant concentration, distribution of surfactant
in the feed, initiator concentration and solid content, on the monomer
conversion, terpolymer composition, and total number of polymer parti-
cles on the kinetics of high solid content terpolymerization of VA, BA, and
MMA. Polymerization rate was reported to be independent of the number
of particles. A high value of an average number of radicals per particle of
the system suggested that the radical termination in aqueous phase was
negligible.
Ya n g et al. [80] prepared an emulsion polymer by using monomers MMA,
BA, 2-EHA, acrylic acid, and 2-hydroxyethylmethacrylate (2-HEMA) in
the presence of KPS and SLS as initiator and emulsii er, respectively. h e
ef ects of the ratio of emulsii ers and their concentration, the amount of
initiator, the functional monomers and ratio of monomers on the emulsion
polymerization and the i lm performance were studied. h e ef ect of the
type and amount of surfactant on the overall polymerization features and
i nal product properties for the seeded semicontinuous emulsion terpo-
lymerization of 2-EHA, styrene, and methacrylic acid were investigated by
Masa et al. [81]. h ey found that the type and amount of surfactant had no
ef ect on the polymerization rate, and the viscosity of the latexes decreased
as the amount of emulsii er increased.
6.2.1.2 Initiator
In emulsion polymerization, the reaction is initiated by addition of either
water-soluble (thermal or redox) or oil-soluble initiator. Water-soluble ini-
tiator produces the free radicals in aqueous phase, whereas oil-soluble ini-
tiator produces the free-radicals in monomer-swollen micelle, monomer
droplets, monomer-swollen polymer particles and to some extent in aque-
ous phase. So the loci of polymerization with dif erent initiator systems
bring in dif erent kinetics and mechanism of polymerization. Mostly, the