scholarly journals Effects of Initiator Homolysis Rate Constant on Kinetics and Chain Length Distribution in Living Free-Radical Polymerization

1999 ◽  
Vol 31 (7) ◽  
pp. 585-589 ◽  
Author(s):  
Junpo He ◽  
Hongdong Zhang ◽  
Li Li ◽  
Chengming Li ◽  
Jizhuang Cao ◽  
...  
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Rate Constant ◽  
Length Distribution ◽  
Free Radical Polymerization ◽  
Chain Length Distribution ◽  
Living Free Radical Polymerization

scholarly journals Method of Moments Applied to Most-Likely High-Temperature Free-Radical Polymerization Reactions

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 656 ◽  
Author(s):  
Hossein Riazi ◽  
Ahmad Arabi Shamsabadi ◽  
Michael Grady ◽  
Andrew Rappe ◽  
Masoud Soroush
Keyword(s):  
High Temperature ◽  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Method Of Moments ◽  
Length Distribution ◽  
Free Radical Polymerization ◽  
Polymer Chains ◽  
Rate Equations ◽  
Chain Length Distribution

Many widely-used polymers are made via free-radical polymerization. Mathematical models of polymerization reactors have many applications such as reactor design, operation, and intensification. The method of moments has been utilized extensively for many decades to derive rate equations needed to predict polymer bulk properties. In this article, for a comprehensive list consisting of more than 40 different reactions that are most likely to occur in high-temperature free-radical homopolymerization, moment rate equations are derived methodically. Three types of radicals—secondary radicals, tertiary radicals formed through backbiting reactions, and tertiary radicals produced by intermolecular chain transfer to polymer reactions—are accounted for. The former tertiary radicals generate short-chain branches, while the latter ones produce long-chain branches. In addition, two types of dead polymer chains, saturated and unsaturated, are considered. Using a step-by-step approach based on the method of moments, this article guides the reader to determine the contributions of each reaction to the production or consumption of each species as well as to the zeroth, first and second moments of chain-length distributions of live and dead polymer chains, in order to derive the overall rate equation for each species, and to derive the rate equations for the leading moments of different chain-length distributions. The closure problems that arise are addressed by assuming chain-length distribution models. As a case study, β-scission and backbiting rate coefficients of methyl acrylate are estimated using the model, and the model is then applied to batch spontaneous thermal polymerization to predict polymer average molecular weights and monomer conversion. These predictions are compared with experimental measurements.

The Kinetics of Free-Radical Polymerization: Fundamental Aspects

2002 ◽  
Vol 55 (7) ◽  
pp. 399 ◽  
Author(s):  
G. T. Russell
Keyword(s):  
Molecular Weight ◽  
Steady State ◽  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Free Radical Polymerization ◽  
Length Dependence ◽  
Model Independent ◽  
Living Free Radical Polymerization ◽  
Kinetics Of

Some fundamental aspects of the kinetics of free-radical polymerization are reviewed. So-called classical results for rate and molecular-weight distribution are first of all presented. It is shown how this approach can be built upon when chain-length-dependent termination is allowed, which it always should be. Various termination models are considered, and it is illustrated that although the models are different, rather remarkably they give common, model-independent behaviour. Some leading experimental results regarding the chain-length dependence of termination are summarized, before the chain-length dependence of other reactivities, the variation of reactivities with conversion, and non-steady state experiments are briefly discussed. Finally, living free-radical polymerization as effected by a reversible termination agent is considered. An outline of the kinetics of these systems is given, with the oft-neglected importance of conventional termination being stressed.

Living free radical polymerization (RAFT) of dodecyl acrylate: Chain length dependent termination, mid-chain radicals and monomer reaction order

Polymer ◽  
2005 ◽  
Vol 46 (18) ◽  
pp. 6797-6809 ◽  
Author(s):  
Alexander Theis ◽  
Achim Feldermann ◽  
Nathalie Charton ◽  
Thomas P. Davis ◽  
Martina H. Stenzel ◽  
...  
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
Chain Length ◽  
Reaction Order ◽  
Free Radical Polymerization ◽  
Living Free Radical Polymerization
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