Suggested interpretation for the anomalous kinetics of acrylonitrile polymerization in homogeneous solution

Abstract

Abstract The polymerization in homogeneous solution of acrylonitrile shows an anomalous kinetic behavior. The reaction order in respect to the monomer appears higher than 1, and approaches the order of 2 at low acrylonitrile concentrations (< 2 M ). This behavior was given various interpretations. No completely satisfactory explanation is, however, available. By taking into account some secondary radical reactions recently discovered (polymerization through CN), a new interpretation of the kinetic anomalous behavior is suggested, and a kinetic model is given which also takes into account the propagation through the triple CN bond. The equations so fully derived justify the experimental results. A reaction order of 2 in respect to the monomer for (AN) tending to zero, and approaching 1 for (AN) > 2 M , is deduced from the assumptions made. According to the proposed mechanism, the kinetic deviations from theory do not depend on the initiation rate, as confirmed by experimental results, but only on monomer concentration.