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Kinetic modelling in living polymerizations: The effect of modifiers on the degree of polymerization in batch and continuous stirred‐tank reactors
Author(s) -
Puskas Judit E.
Publication year - 1993
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.1993.040020110
Subject(s) - continuous stirred tank reactor , polymerization , chemistry , cyclohexane , polymer chemistry , chain transfer , degree of polymerization , solution polymerization , batch reactor , transfer agent , solvent , chemical engineering , thermodynamics , polymer , radical polymerization , organic chemistry , catalysis , physics , engineering
Abstract Equations for the calculation of the degree of polymerization in 'modified' living polymerizations (living polymerizations in the presence of deliberately added terminating and transfer agents) are developed from a mechanistic/kinetic model. It is shown that a modifier, acting by the mechanism discussed, would cause more chain transfer in a continuous stirred tank reactor (CSTR) than in a batch. This is found to be the case in the living polymerization of 1,3‐butadiene initiated by butyllithium in nonpolar solvents, such as cyclohexane, when 1,2‐butadiene was used as a modifier. Under similar conditions no chain transfer was detected in batch polymerizations, while ≈ 20% transfer was found in a CSTR. The equations developed can be used to calculate the ratio of the rates of propagation and termination, k p / k t . CSTR data yielded k p / k t ≈ 480 at 90°C; re‐evaluation of batch data published earlier by Adams et al. for the same system in hexane solvent yields k p / k t ≈ 1250 and 670 at 50° C and 70°C, respectively.