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Establishing mechanisms for emulsion polymerizations
Author(s) -
Casey Brendan S.,
Maxwell Ian A.,
Morrison Bradley R.,
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.19900310103
Subject(s) - emulsion polymerization , nucleation , chain propagation , diffusion , emulsion , mechanism (biology) , chemistry , thermodynamics , monomer , polymerization , polymer chemistry , chemical physics , polymer , physics , organic chemistry , quantum mechanics
Emulsion polymerization systems are so complex that different workers often believe contradictory mechanisms for ostensibly the same system. A number of case studies are examined wherein data have been obtained that are able to refute mechanistic postulates (as distinct from supporting a mechanism by showing that a mathematical model incorporating it is able to reproduce a limited range of data). These examples are: (1) particle nucleation (refutation of micellar entry); (2) free radical desorption (refuting its unimportance for systems with insoluble monomers, and showing that the transfer/diffusion mechanism for this process is suspect); (3) entry (refutation of 100% initiator efficiency); (4) propagation (refutation of the assumption that the propagation rate coefficient (k p ) drops to zero at the glass transition); and (5) termination (refutation of the assumption that dependence on lengths of each chain can always be ignored).