ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
To elucidate some details of the mechanism of isoprene polymerization by means of the complex catalyst TiCl4 + Al(i-C4H9)3 an analysis has been made of the data on the molecular weight distribution of the polymers. A relation has been established between the heterogeneous character of the polymerization process and the degree of dispersity of the polymer. In particular, it has been shown that for very small catalyst particles polymerization proceeds slowly and is a nonstationary process. The molecular weight distribution of the polymers changes with time. On increasing the catalyst particle size above certain, critical dimensions required for carrying out heterogeneous catalysis, a stationary molecular weight distribution of the polymers sets in, remaining unchanged up to the end of the process. An investigation of the molecular weight distribution of the polymers obtained at various catalyst component ratios and various methods of addition to the monomer permitted a number of details of the chain termination mechanism in catalytic polymerization to be elucidated. Chain breaking has been shown to be not the result of reversible interaction of growing chains with the active centers on the surface.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1961.1205215740
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