Simultaneous measurement of free radical decay in polymerization of MMA initiated by AIBN using ESR and its kinetic model

The kinetics of free radical decay in the polymerization of MMA initiated b y AIBN was studied by means of ESR spectroscopy. It was found that the curv es of radical decay are strongly associated with the reaction temperature, the initiator concentration and the solvent. In the case of the radical pol ymerization carried out at high temperature or in solution, the radical con centration first reached a maximum, then declined monotonously with reactio n time. It was also found that the greater the amount of initiator or the h igher the temperature, the more rapidly the radicals decay. When the bulk p olymerization was implemented at a relatively low temperature, the curves o f radical decay became more complicated, i.e., the radical concentration ra pidly rose to a maximum, then dropped to a minimum, finally increased again with reaction time. Taking into account the diffusion effect, a semi-empir ical equation is suggested to describe the kinetics of propagating radical decay.