Kinetics of nucleation-controlled polymerization of N,N′-bismaleimide-4,4′- diphenylmethane/barbituric acid

Abstract

Non-isothermal polymerization kinetics of N,N′-bismaleimide-4,4′-diphenylmethane (BMI)/barbituric acid (BTA) was investigated by using DSC. Comparable extents of Michael addition reaction estimated independently by a molecular probe, hydroquinone (HQ), and the deconvolution technique using the Haarhoff-Van der Linde (HVL) function were achieved. Both the model-fitting and model-free methods were employed to determine the kinetic parameters for the polymerization of BMI/BTA. The kinetic parameters of the BMI/BTA system for the three distinct stages were determined by the model-free method with the aid of the deconvolution technique. The particle nucleation involved in the polymerization process was satisfactorily predicted by the nucleation Avrami-Erofeev models {f(α)=n(1−α)[−ln(1−α)](n−1)/n} with n=1.61 for Stage 1, n=2.24 (Stage 2) and n=2.77 (Stage 3). Microgel particles (MPs) of BMI/BTA were generated during polymerization. The particle size (d, z-average) of MPs was measured by dynamic light scattering (DLS). The least-squares best-fitted d versus t profile attained is d=1×10−4t3−1.82×10−2t2+1.044t−2.133 at 100°C.