Mechanisms and kinetics of non-isothermal polymerization of N,N′-bismaleimide-4,4′-diphenylmethane with 2-thiobarbituric acid

Mechanisms and kinetics of non-isothermal polymerization of N,N′-bismaleimide-4,4′-diphenylmethane (BMI) with 2-thiobarbituric acid (TBTA) were investigated. Competition among free radicals polymerization, Michael addition reaction and aza-Michael addition reaction mechanisms for the BMI/TBTA reaction system was characterized by using differential scanning calorimeter (DSC), electron spin resonance (ESR) and 1H-NMR techniques. Both radical polymerization and (aza) Michael reaction mechanisms played an important role in the reaction system. Model-free (isoconversional) method was used to determine triplet kinetic parameters for the polymerization of BMI with TBTA. Average activation energy (Eα) and pre-exponential factor (Aα) are ca. 71 kJ  mol−1 and 17.85 × 107 min−1 in the fractional conversion (α) range 0.1-0.9, respectively. The polymerization of BMI with TBTA is primarily reaction-controlled [f(α) = (1−α)].