Aqueous Polymerization of Acrylonitrile by Persulphate Disulphite Redox System Catalysed by Mn2+Ion: A Kinetic Study

Polymerization of the acrylonitrile monomer (M), initiated by a persulphate -Mn?+- disulphite redox system was investigated kinetically, over a temperature range of 25-45?C in aqueous medium under oxygen atmosphere. The incorporation of metal ion, Mn?+, with persulphate - disulphite redox system and rate of polymerization (Rp) has been studied at various concentrations of monomer and initiator. The polymerization exhibited a strong dependence on the concentration of Mn?+. That is, at low concentration of Mn?+, Rp? [M] [S?O82-]1/2 [HSO3-]1/2while at high Mn?+ concentration, Rp? [M] [S?O82-]1/2 [Mn?+]1/2. The degree of polymerization is found to increase with increase in concentration of monomer and decrease in concentration of persulphate, manganese, and disulphite. The influence of organic solvents and temperature on the rate of polymerization has also been investigated and energy of activation was calculated to be 30.6 k J/mol. On the basis of experimental results, a suitable scheme has been proposed and a rate expression has been derived.