ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The chromocene catalyst for ethylene polymerization shows a high response to hydrogen which leads directly to highly saturated polyethylenes containing methyl groups as the major terminal functionality in the polymers. At a polymerization temperature of 90°C the ratio of termination rate constants for hydrogen (kH) and ethylene (kM) is kH/kM = 3.60 × 103. The ratio of kH to the chain propagation constant (kp) is kH/kp = 4.65 × 10-1 A simple relation that can be derived from polymerization kinetics and the Quackenbos equation exists between melt index and hydrogen-ethylene ratio. A deuterium isotope effect (kH/kD) = 1.2 was calculated for the termination reaction. The overall polymerization process has an apparent activation energy of 10.1 kcal/mole. Oxygen addition studies show catalyst activity is proportional to initial divalent chromium content.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1973.170110208
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