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Crosslinking kinetics in emulsion polymerization
Author(s) -
Tobita Hidetaka,
Hamielec Archie E.
Publication year - 1993
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990300207
Subject(s) - polymerization , monomer , polymer chemistry , radical , radical polymerization , emulsion polymerization , kinetic chain length , polymer , kinetics , materials science , bulk polymerization , copolymer , reactivity (psychology) , chemistry , photochemistry , chemical engineering , organic chemistry , composite material , medicine , physics , alternative medicine , pathology , quantum mechanics , engineering
Network formation in free‐radical polymerization is investigated both from experimental and theoretical points of view. In a bulk free‐radical crosslinking copolymerization, the radical concentration increases significantly due to a decrease in the bimolecular termination rate. Some fraction of radicals is trapped during the course of network formation, and the reactivity of the radicals in liquid state is completely different from that in solid state (trapped radicals) in terms of both propagation and termination. In emulsion crosslinking polymerization, the crosslinking density tends to be fairly high even from the start of the polymerization. The crosslinking density development is substantially different from that in bulk and solution polymerizations, in which the crosslinking density increases with time, at least in the earlier stages of polymerization. Due to the elastic contribution of free energy change, the monomer concentration in the polymer particles is lower than for linear emulsion polymerizations as long as the monomer droplets exist, resulting in an enhanced tendency toward crosslinking reactions.