ISSN:
0449-2951
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
A study has been carried out to determine the polymeric transfer constants of poly(vinyl acetate), polystyrene, and poly(methyl methacrylate) in the polymerization of vinyl acetate, as well as the similar transfer constants of poly(vinyl acetate) in the polymerization of styrene and methyl methacrylate. As before, this was accomplished by polymerizing each monomer in the presence of varying amounts of the desired oligomer and separating the resulting polymers. The effect of oligomer endgroups was checked by using oligomers of different molecular weight (1000-5000). As found previously for styrene and methyl methacrylate, there was no noticeable effect of polymeric endgroups on transfer activity, hence the transfer constants found refer to the interior units in the chain. The values of the various transfer constants are given. As expected, the vinyl acetate radical showed a reactivity in hydrogen abstraction which was several orders of magnitude greater than that of the styrene radical, and at least one order of magnitude greater than that of methyl methacrylate. The absolute values of the activation energy for the transfer step were remarkably similar, the difference in transfer activity being largely due to the difference in activation energy of the propagation reaction, and also to steric considerations.
Zusätzliches Material:
10 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1963.100011004
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