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Unexpected effect of the monomer concentration on the rate of a radical polymerization
Author(s) -
Casinos Ismael
Publication year - 1994
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.1994.210330408
Subject(s) - radical , monomer , polymerization , polymer chemistry , chemistry , radical polymerization , methyl methacrylate , kinetic chain length , photochemistry , polymer , chain termination , cobalt mediated radical polymerization , redox , organic chemistry
The radical polymerization of vinyl monomers is usually initiated by physical and chemical means. After an increasing polymerization rate, R p , at low monomer concentrations, some reactive systems show an unexpected minimum for R p at high enough monomer concentrations. The radical polymerization of methyl methacrylate (MMA) initiated by the redox system D ‐glucose–ceric ion at varying MMA concentration is discussed. The peculiar behaviour of R p is explained by the presence of two circumstances: the initiation rate from D ‐glucose radicals does not depend on MMA concentration when most of the D ‐glucose radicals formed react by adding to monomer, and the radical chains initiated by D ‐glucose radicals undergo mutual termination with a portion of the radical chains initiated by monomer radicals. Some information about the nature of the polymer end‐groups is reached from the mechanistic approach.