Mechanisms and kinetics of non-isothermal polymerization of N,N′-bismaleimide-4,4′-diphenylmethane with 1,3-dimethylbarbituric acid

Mechanisms and kinetics of non-isothermal polymerization of N,N′-bismaleimide-4,4′-diphenylmethane (BMI) with 1,3-dimethylbarbituric acid (13BTA) were investigated. Competition between free radical polymerization and Michael addition reaction mechanisms for the BMI/13BTA reaction system was characterized by using DSC and 1H NMR technique. Model-free (isoconversional) method was used to determine triplet kinetic parameters for the polymerization of BMI with 13BTA. Average activation energy (Eα) and pre-exponential factor (Aα) are ca. 56 kJ mol−1 and 65.83 × 105 min−1 in the fractional conversion (α) range 0.1-0.9, respectively. Particle nucleation involved in the polymerization process was satisfactorily predicted by the nucleation Avrami-Erofeev model {f(α) = n(1 − α)[−ln(1 − α)](n−1)/n} with n = 1.46. The z-average particle size of microgel particles was measured by dynamic light scattering, which supported the particle nucleation and growth process.