ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Measurement of butadiene absorption at constant volume, and of polymer formation, indicated that the rate of polymerization was first order in monomer concentration, up to 1.5 mole/l., and also in initial total catalyst concentration, for given molar ratio of alkyl to titanium ester. The overall activation energy was 11.5 kcal./mole. A fast initiation, accompanied by the evolution of ethylene or a mixture of ethane and ethylene, a relatively slow propagation, and chain transfer to monomer, appeared to be the main steps of the reaction. Termination was essentially absent. Insoluble, gellike material was formed roughly at 20% conversion and was attributed to a random crosslinking, involveing very few crosslinks per molecule, or possibly trifunctional branching. The molecular weight distribution was very narrow. A polymer of over 80% in 1,2 units, having a predominantly syndiotactic structure and about 10% crystallinity, was obtained. In the absence of monomer, the catalyst components reacted rapidly to form complexes, accompanied by strong ethane evolution. A complex series of reactions leading to the possible formation of more than one active species was indicated. The active catalyst suffered bimolecular decomposition on prolonged standing. For optimal molar ratio of alkyl to ester of 5/1, the concentration of active species was estimated as having an upper limit of 4.8 × 10-6 mole/l.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1964.100020703
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