The “group-termination coefficient” in the analysis of kinetic schemes of polymerizations with size-dependent termination coefficients

✍ Scribed by C.H. Bamford

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 509 KB
• Volume: 25
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(89)90029-3

✦ Synopsis

The concept of the "group-termination coefficient" is described together with its applications to the kinetic treatment of free-radical polymerizations in which the termination coefficient is a function of radical size. Basically the procedure involves the mean size of a group of radicals and the total radical concentration and leads to expressions for the (instantaneous) radical size distribution and related kinetic functions equivalent to those of the geometric mean approximation. Systems considered in this paper are simple free-radical polymerizations, polymerizations with chain transfer, polymerizations with ideal retardation and systems showing degradative addition to monomer. Rather simple expressions are derived for radical size distributions and mean radical sizes, rates of polymerization, mean kinetic chain lengths and effective mean termination coefficients. The treatment is thus shown to provide a convenient method for analysing the kinetics of a wide variety of free-radical polymerizations. E = <p{mc/(1 + l)(1 + c)b}.~, ¢ = tp[{b + mc/(1 + I)(1 + c)}/l] .