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Kinetic study of the free‐radical polymerization of vinyl acetate in the presence of deuterated chloroform by 1 H‐NMR spectroscopy
Author(s) -
Semsarzadeh Mohammad Ali,
Abdollahi Mahdi
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.28536
Subject(s) - chemistry , azobisisobutyronitrile , chloroform , reaction rate constant , solvent , polymerization , monomer , solvent effects , chain transfer , analytical chemistry (journal) , polymer chemistry , radical polymerization , kinetics , organic chemistry , polymer , physics , quantum mechanics
Abstract The free‐radical polymerization of vinyl acetate was performed in the presence of deuterated chloroform (CDCl 3 ) as a chain‐transfer agent (telogen) and 2,2′‐azobisisobutyronitrile as an initiator. The effects of the initiator and solvent concentrations (or equivalent monomer concentration) and the reaction temperature on the reaction kinetics were studied by real‐time 1 H‐NMR spectroscopy. Data obtained from analysis of the 1 H‐NMR spectra were used to calculate some kinetic parameters, such as the initiator decomposition rate constant ( k d ), k p ( f / k t ) 1/2 ratio (where k p is the average rate constant for propagation, f is the initiator efficiency, and k t is the average rate constant for termination), and transfer constant to CDCl 3 ( C CDCl 3). The results show that k d and k p ( f / k t ) 1/2 changed significantly with the solvent concentration and reaction temperature, whereas they remained almost constant with the initiator concentration. C CDCl 3changed only with the reaction temperature. Attempts were made to explain the dependence of k p ( f / k t ) 1/2 on the solvent concentration. We concluded from the solvent‐independent C CDCl 3values that the solvent did not have any significant effect on the k p values. As a result, changes in the k p ( f / k t ) 1/2 values with solvent concentration were attributed to the solvent effect on the f and/or k t values. Individual values of f and k t were estimated, and we observed that both the f and k t values were dependent on the solvent (or equivalent monomer) concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008