ABSTRACT:The kinetics of aqueous polymerization of the symmetrical nonconjugated divinyl monomer N,N-methylenebis(acrylamide) (MBA), was studied at 35ЊC and at constant ionic strength under nitrogen atmosphere involving potassium peroxydiphosphate (PDP) as oxidant with three different activators thiolactic acid (TLA), thiomalic acid (TMA), and thioglycollic acid (TGA). The rate of polymerization, R P , and rate of disappearance of peroxydiphosphate, 0R PDP have been followed while polymerization was initiated separately by the PDP-TLA/PDP-TMA/PDP-TGA redox systems. R P for the above three systems showed first-order dependences on both [ [activators] were observed with respect to 0R PDP in the above three systems. A reaction mechanism which involves complex formation between PDP and thiocarboxylic acid, propagation through intramolecularintermolecular reactions, degradative chain transfer reaction of the growing radical with PDP, and linear termination by the interaction of the chain radical with primary radical was proposed. The kinetic parameters for the three polymerization systems were calculated and compared.