Aqueous polymerization of acrylic acid initiated by KMnO4 — H2C2O4 redox system

Polymerization of acrylic acid in aqueous solution initiated by permanganate-oxalic acid redox pair has been studied at 32 ± 0.2°C in nitrogen atmosphere. The rate of polymerization has been found to be nearly independent of oxalic acid concentration within the range 1.87 to 9.33 · 10^?3 mole/l. and decreases only at higher concentrations of the oxalic acid. The rate has also been found to vary with the first power of the monomer concentration (within the range 1.44 to 5.76 · 10^?2 mole/l.) and the first power of the catalyst concentration (8.0 to 28.0 · 10^?5 Mole/l.). It is, however, proportional to half power at relatively high catalyst concentration, at fixed concentrations of oxalic acid (1.03 · 10^?2 mole/l.) and the monomer (5.76 · 10^?2 mole/l.). At higher concentration of monomer the catalyst exponent has been found to be nearly unity for both the higher and lower concentrations of the catalyst. The initial rate of polymerization increases with increase in temperature. The overall energy of activation has been found to be 19.56 kcal/mole within the temperature range 30 – 45°C. Organic solvents and salts (KCI, Na₂SO₄, and Na₂C₂O₄) depress the rate but MnSO₄ 4H₂O has been found to increase the initial rate but depress the maximum conversion.