I. Capek et al., Effect of temperature on styrene emulsion polymerization in the presence of sodium dodecyl sulfate. II, J POL SC PC, 38(9), 2000, pp. 1477-1486
Citations number
27
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
The batch emulsion polymerization kinetics of styrene initiated by a water-
soluble peroxodisulfate at different temperatures in the presence of sodium
dodecyl sulfate was investigated. The curves of the polymerization rate ve
rsus conversion show two distinct nonstationary-rate intervals and a should
er occurring at a high conversion, whereas the stationary-rate interval is
very short. The nonstationary-state polymerization is discussed in terms of
the long-term particle-nucleation period, the additional formation of radi
cals by thermal initiation, the depressed monomer-droplet degradation, the
elimination of charged radicals through aqueous-phase termination, the rela
tively narrow particle-size distribution and constant polydispersity index
throughout the reaction, and a mixed mode of continuous particle nucleation
. The maximum rate of polymerization (or the number of polymer particles nu
cleated) is proportional to the rate of initiation to the 0.27 power, which
indicates lower nucleation efficiency as compared to classical emulsion po
lymerization. The low activation energy of polymerization is attributed to
the small barrier for the entering radicals, The overall activation energy
was controlled by the initiation and propagation steps. The high ratio of t
he absorption rate of radicals by latex particles to the formation rate of
radicals in water can be attributed to the efficient entry of uncharged rad
icals and the additional formation of radicals by thermally induced initiat
ion. (C) 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1477-14
86, 2000.