Effect of chain transfer agents on the kinetics and mechanism of particle nucleation in the emulsion polymerization of vinyl pivalate |
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Authors: | Shinya Suzuki Kenji Kikuchi Atsushi Suzuki Takuji Okaya Mamoru Nomura |
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Affiliation: | (1) Department of Materials Science, School of Engineering, The University of Shiga Prefecture, 2500 Hassaka, Hikone 522-8533, Japan;(2) Department of Materials Science and Engineering, Faculty of Engineering, Fukui University, 3-9-1 Bunkyo, Fukui 910-8507, Japan |
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Abstract: | We have studied the kinetics and mechanism of particle nucleation in the emulsion polymerization of vinyl pivalate (VPi) under a wide variety of conditions. Quantitative comparisons between the theoretical and experimental estimations of the average number of radicals per polymer particle, as a function of the amounts of surfactant were performed. The relationship between and the parameter α w, the ratio of radical production in the aqueous phase to termination per particle, can be explained by assuming that chain-transferred monomer radicals escape from the particle. We studied the influence of the chain transfer agents (CTA), namely, n-dibutyl disulfide, t-dibutyl disulfide and l-cysteine in the emulsion polymerization. The addition of a CTA had a strong influence on the resulting degree of polymerization. The experimental results can be accounted on the basis of a kinetic analysis of the chain transfer reaction, assuming an increase of the rate of escape of chain-transferred radicals from the polymer particle. |
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Keywords: | Vinyl pivalate Emulsion Kinetics Chain transfer agents Sodium lauryl sulfate |
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