Solvation effect in the thermal decomposition of 2,2'-azoisobutyronitrile. The rate of initiation of the polymerization of methyl methacrylate in N,N-dimethylformamide
Polimery 2002, No 11-12, 822
Induction time (ti) and initiation rate (2kd . j) of methyl methacrylate (MMA) polymerization in N,N-dimethylformamide (DMF) at 60 °C, initiated with 2,2'-azobisisobutyronitrile (AIBN), as functions of a monomer (M)/solvent (S) ratio [expressed as monomer mole fraction i.e. XM = M / (M + S)] have been studied. It has been stated that (2kd . j) = f(xM) dependence is linear in the whole range of xM variability. This dependence has been compared with the dependence of initiator's thermal decomposition constant kd as a function of xM, which is curvilinear and shows a minimum in the range of xM = 0.2-0.3. There was also determined the initiation efficiency - as a function of xM, which results from formerly discussed dependence's i.e. (2kd . j) = f(xM) and (kd) = f(xM), and shows - according to the expectations - characteristic maximum in the range xM = 0.2-0.3. The courses of all three discussed dependence's have been interpreted on the bas e of a model of initiator solvation by monomer (IM) and solvent (SIS) as well as mixed solvation (MIS).
Keywords: methyl methacrylate radical polymerization, thermal initiation, 2,2'-azoisobutyronitrile thermal decomposition, initiator solvation