Barbara Pabin-Szafko

Solvation effect in thermal decomposition of 2,2'-azoisobutyronitrile on the N,N-dimethylformamide/acrylonitrile system

The thermal decomposition rate constant of AIBN (kd) in N, N-dimethylformamide (DMF)/acrylonitrile (AN) mixtures of various compositions at 60°C is studied. The kd value is (6.45 ± 0.3) × 10−4 min−1 for pure DMF and (7.20 ± 0.3) × 10−4 min−1 for pure acrylonitrile. The kd values of DMF/AN mixtures were found to be dependent on the mixture composition. This dependence is not a linear function of the monomer mole fraction (xM), but has a minimum at ca. 70 mol % of AN. The relationship kd = f(xM) has been interpreted on the basis of the hypothesis of initiator solvation by monomer AN and solvent DMF.

Solvation effect in the thermal decomposition of 2,2′‐azoisobutyronitrile in the three‐component system

The thermal decomposition rate constant (kd ) of 2,2′-azoisobutyronitrile in acrylonitrile (AN; monomer A)–methyl methacrylate (MM; monomer B) comonomer mixtures in N,N-dimethylformamide (DMF) as a function of the comonomer mixture composition and its concentration in the solvent at 60 °C was studied. The dependences kd = f(xA ,C) [xA (mole fraction of A in the comonomer mixture) = A/(A + B) = A/C, where C is the comonomer mixture concentration] have a different course as a function of C: from a curve kd = f(xA ) approaching the straight line (C = 2 mol · dm−3) to a convex curve possessing a maximum at a point xA = 0.7 (C = 4 mol · dm−3) to a curve with a flattened wide maximum within the range of xA = 0.2–0.8 (C = 7 mol · dm−3) to a curve with the shape of a lying s (C = 9 mol · dm−3). All the courses of the experimental dependences kd = f(xA ,C) can be explained with a hypothesis of initiator solvation by the comonomers AN and MM and the solvent DMF. The existing solvated forms, their relative stability constants, the thermal decomposition rate constants, and the relative contents in the system were determined.