Polymerization of acrylonitrile initiated by Ce⁴⁺/Thiourea system

Abstract

Kinetics of polymerization of acrylonitrile initiated by the Ce⁴⁺-thiourea redox system have been investigated at 10°. The rate of monomer disappearance is proportional to (a) (monomer concentration)², (b) thiourea concentration and, (c) (ceric ion concentration)^-1. The rate of ceric disappearance is proportional to the ceric and thiourea concentrations, but independent of monomer concentration. A kinetic scheme has been proposed involving production of initiating radicals from oxidation of thiourea by ceric ions and termination exclusively by the interaction of the chain radicals with ceric ions. The scheme is consistent with experimental findings. The results obtained either in the presence or the absence of the reducing agent have been compared and interpreted in terms of the proposed kinetic scheme.