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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 277 (1999), S. 1205-1209 
    ISSN: 1435-1536
    Keywords: Key words Monodisperse micron-sized polystyrene particles ; Urethane acrylate ; Particle diameter ; Particle number density ; Polymerization rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Monodisperse micron-sized polystyrene particles crosslinked using urethane acrylate were produced by dispersion polymerization in ethanol solution and the effect of the crosslinked network structure on the polymerization procedure was studied. The influences of the concentrations of the initiator and urethane acrylate on the particle diameter (D n), the particle number density (N p), and the polymerization rate (R p) were found to obey the approximate relationships D n ∝ [initiator]0.43 [urethane acrylate]0.05, N p ∝ [initiator]−1.30 [urethane acrylate]0.19, and R p ∝ [initiator]0.24 ± 0.02. The power-law dependence of D n and N p on the initiator concentration showed a similar trend to that of linear polystyrene reported in the literature. Especially, it was found that urethane acrylate does not have a serious effect on D n and N p of the particles produced. The dependence of R p on the initiator concentration was observed to be higher than that of linear polystyrene, suggesting that there is still competition between heterogeneous polymerization and solution polymerization because of the crosslinked network structure of the primary particle.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1536
    Keywords: Key words Nucleated particle formation ; Urethane acrylate ; Turbidity measurement ; Boundary concentration ; Stage of particle growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The procedure of nucleated particle formation and particle growth in dispersion polymerization was studied with the intention of understanding the production of monodisperse polystyrene particles cross-linked with urethane acrylate (UA). The time required for the formation of primary particles was determined exactly from the turbidity measurement of the reaction mixture with the polymerization time. It could be found that differing from conventional divinyl cross-linkers, such as divinylbenzene, UA had a boundary concentration where the association and coagulation of preformed nuclei with other oligomers and/or nuclei effectively took place until the primary particle formed. Similarly to linear polystyrene particles, the particle number density of the primary particles cross-linked with UA remained constant to the final particles. This observation verifies the suggestion that the primary particles cross-linked with UA readily absorbed the monomers from the medium during the stage of particle growth.
    Type of Medium: Electronic Resource
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