Effects of initial composition and temperature on the kinetics of polymerizations of N,N′-bismaleimide-4,4′-diphenylmethane with barbituric acid

Kinetics of polymerizations of N,N′-bismaleimide-4,4′-diphenylmethane (BMI)/barbituric acid (BTA) with molar ratios of BMI to BTA equal to 1/1, 2/1 and 4/1 in the temperature range 373-403 K were studied. Both Michael addition polymerization and free radical polymerization mechanisms were operative in such reaction systems. With the knowledge of kinetic parameters of the Michael addition polymerization of BMI with BTA taken from the literature, optimized kinetic parameters for simultaneous free radical polymerization including the overall initiation rate constant and the combined propagation and termination rate constants were achieved. In addition, modeling results along with experimental gelation time data showed that contribution of free radical polymerization was promoted for the polymerization carried out at a higher reaction temperature and/or a larger molar ratio of BMI to BTA. By contrast, Michael addition polymerization was enhanced with a smaller molar ratio of BMI to BTA and/or a lower reaction temperature.