Polymerization of acrylonitrile initiated by thiourea-vanadium(V) redox system

The kinetics of polymerization of acrylonitrile initiated by V⁵⁺-thiourea or V⁵⁺-ethylene thiourea have been studied at 30, 35 and 40°C in nitrogen. The rates of polymerization and V⁵⁺ disappearance, and the chain lengths of polymers were measured. The kinetics are consistent with the formation of an intermediate complex between the thiol form of thiourea or ethylene thiourea and the oxidant decomposition of which leads to the initiating radical. The effects of certain organic solvents (water miscible) and salts on the rate of polymerization have been studied. A kinetic scheme has been proposed and the various rate and energy parameters evaluated.