Kinetics of the aqueous polymerization of acrylamide initiated by the permanganate‐ tartaric acid redox system

Abstract

Abstract The kinetics of the aqueous polymerization of acrylamide, initiated by the permanganate/tartaric acid redox system was studied at 35±0,2°C under nitrogen. The initial rate of polymerization remains independent of the tartaric acid concentration in the range 3,3.10 —3 to 9,9.10 —3 mol/dm 3 . The order of the reaction with respect to the catalyst concentration (catalyst exponent) is found to be 0,55, indicating a bimolecular mechanism for the termination reaction. The rate of polymerization varies linearly at low monomer concentrations (1,25.10 —2 to 5,0.10 —2 mol/dm 3 ). With increase in temperature above 35°C, the initial rate increases but the conversion decreases. The overall energy of activation is found to be 18,68 kcal/mol (78,10kJ/mol) in the temperature range 30 to 50°C. Water miscible organic solvents and neutral salts depress both the rate and the conversion. Addition of MnSO 4 or the injection of more catalyst at intermediate stages raises both the initial rate and the maximum conversion. NaF decreases the rate but increases the conversion.