Aqueous polymerization of acrylamide initiated by acidic permanganate/thiourea redox system

Abstract

Abstract The polymerization of acrylamide, initiated by acidic permanganate/thiourea redox system, was studied in aqueous media at 30 ± 0,2 °C in nitrogen. The rate of polymerization ( R p ) was found to be proportional to nearly the first power of the catalyst (KMnO 4 ) concentration, within the range of 0,5 · 10 −2 to 1,4 · 10 −2 mol dm −3 , and independent of the thiourea concentration. However, the rate of polymerization varies with the first power of the hydrochloric acid concentration within the range of 2,85 · 10 −2 to 11,4 · 10 −2 mol dm −3 , and increases linearly up to certain extent by varying the monomer concentration from 2,5 · 10 −2 to 12,5 · 10 −2 mol dm −3 . A deviation from the linear behaviour is observed, however, above a concentration of 12,5 · 10 −2 mol dm −3 . The initial rate of polymerization ( R i ) as well as the maximum conversion increases by increasing the temperature up to 35 °C, but the maximum conversion falls as the temperature rises above 35 °C. The overall energy of activation is found to be 47,70 kJ mol −1 (11,48 kcal/mol −1 ) within the temperature range of 25–45 °C. Addition of salts, except manganous salts, was found to be associated with a depression in the R p and maximum conversion. The effect of cationic and anionic surfactants has been found to increase and decrease the R p respectively; non‐ionic detergents, however, have no effect on the R p .