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High‐conversion emulsion, dispersion and suspension polymerization
Author(s) -
Adams Mary E,
Casey Brendan S,
Mills Martin F,
Russell Gregory T,
Napper Donald H,
Gilbert Robert G
Publication year - 1990
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19900350103
Subject(s) - emulsion , dispersion (optics) , monomer , diffusion , emulsion polymerization , kinetics , polymerization , polymer , chemical physics , thermodynamics , suspension (topology) , materials science , polymer chemistry , chemistry , chemical engineering , optics , physics , classical mechanics , organic chemistry , composite material , engineering , mathematics , homotopy , pure mathematics
Some of the distinguishing features of emulsion polymerization kinetics at high conversion are discussed. The apparent anomaly that propagation rate coefficients deduced from bulk and emulsion systems at high conversion are greatly different actually arises because the initiator efficiency in the former is very low. At intermediate and at high conversions, termination kinetics must take account of the length of each terminating chain; data and a new theoretical model for this are found to be in accord. Modelling the reaction‐diffusion equations at high conversion (including new theory to account for polymer migration) shows that large (say, >200 nm radius) particles at high conversion will show strong spatial inhomogeneity (core‐shell structure) even in emulsion homopolymerizations, because of the slow diffusion of monomer and free radicals.