scholarly journals Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996]

1996 ◽  
Author(s):  
B.J. McCoy ◽  
G. Madras
Keyword(s):  
Molecular Weight ◽  
Time Dependence ◽  
Degradation Kinetics ◽  
Solution Time ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Kinetics Of

The Mechanism Which Restricts Chain Growth in Polymerization with Alkylaluminum-Titanium Tetrachloride Complex Catalysts

1961 ◽  
Vol 34 (3) ◽  
pp. 986-990
Author(s):  
S. E. Bresler ◽  
M. I. Mosevitskiĭ ◽  
I. Ya Poddubnyĭ ◽  
Shi Guan-I
Keyword(s):  
Molecular Weight ◽  
Regular Structure ◽  
Chain Growth ◽  
Time Interval ◽  
Stationary Condition ◽  
Kinetics Of Polymerization ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Kinetics Of ◽  
Isoprene Polymerization

Abstract In the production of polymers having a highly regular structure of the molecular chains, catalyst complexes of the Ziegler type are currently in wide use. The development of mechanisms for the separate steps in the catalytic process is of primary significance. This report outlines some results on a study of the mechanisms involved in isoprene polymerization with complexes formed through the interaction of Al (iso-C4H9)3 and TiCl4; the data were obtained from the sedimentation of the polymers in the ultracentrifuge, in combination with data on the kinetics of polymerization. We have indicated previously1 that in isoprene polymerization using the specified catalysts, the growth of the macromolecules proceeds quite rapidly, the time interval between the first appearance of active chains and the termination of reaction being only a few minutes; subsequently there follows an immediate stationary condition. However, with use of the ultracentrifuge we have obtained molecular weight distributions of polymers which are substantially different from the equilibrium distribution expected from present-day kinetic theories of polymerization. They were characterized by relatively low dispersion and, in the main, strongly distorted by high-molecular bands; in most cases, there was practically a complete absence of molecules with a molecular weight less than 200–300 thousand.

Using molecular weight distributions to determine the kinetics of peroxide-induced degradation of polypropylene

2001 ◽  
Vol 56 (12) ◽  
pp. 3659-3669 ◽  
Author(s):  
Piet D. Iedema ◽  
Claudia Willems ◽  
Ger van Vliet ◽  
Wytske Bunge ◽  
Stan M.P. Mutsers ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Kinetics Of
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