ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
It has been found possible to control the time of growth of polymerizing styrene radicals by adding overwhelming amounts of free radicals at intervals to an emulsion polymerization system. The styrene chains initiated in one addition are mostly terminated in the next addition, so that their growth time is the interval between additions. Polymers with the molecular weights of most of the molecules very narrowly concentrated around selected values can be prepared in this way. Ultraviolet light plus azoisobutyramide has been found to be a practical initiation system for preparing polystyrenes in this way with molecular weights greater than 500,000. The upper limit of the molecular weight obtainable is determined by the rate of chain transfer. For styrene at 0°C. this upper limit appears to be a few millions.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1957.1202510803
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