Product quality improvement in a high-temperature free-radical polymerization reactor

2004 ◽  
Author(s):  
Congling Quan ◽  
M. Soroush ◽  
M.C. Grady
Keyword(s):  
Quality Improvement ◽  
High Temperature ◽  
Free Radical ◽  
Product Quality ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Polymerization Reactor ◽  
Product Quality Improvement

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.

Gas-free initiators for high-temperature free-radical polymerization

2000 ◽  
Vol 38 (21) ◽  
pp. 3984-3990 ◽  
Author(s):  
Jonathan Masere ◽  
Yuri Chekanov ◽  
James R. Warren ◽  
Felicia D. Stewart ◽  
Rabih Al-Kaysi ◽  
...  
Keyword(s):  
High Temperature ◽  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization

scholarly journals Decompositions in the production of low density polyethylene: Reasons, consequences and prevention

2007 ◽  
Vol 61 (6) ◽  
pp. 357-363 ◽  
Author(s):  
Dragoslav Stoiljkovic ◽  
Slobodan Jovanovic ◽  
Jovica Djordjevic ◽  
Budimir Damjanovic
Keyword(s):  
High Pressure ◽  
Free Radical ◽  
Radical Polymerization ◽  
Scientific Literature ◽  
Free Radical Polymerization ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Industrial Practice ◽  
Polymerization Reactor

In the production of low density polyethylene by free radical polymerization of ethylene at high pressure, ethylene and polyethylene occasionally decompose to carbon, hydrogen and methane resulting in an enormous increase of pressure and temperature. Huge explosions occur in a polymerization reactor and in other parts of the installation. In addition to the well known reasons of decompositions, in this work it is pointed out that the polymerization under critical entropy conditions is an additional cause of explosions, which has not been recognized and elaborated in scientific literature and industrial practice.

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