Abstract: The accelerating effect of different ureas [3 - (3 - chloro-4 - methyl-phenyl) -1, 1 - dimethylurea (A); 3 - (3, 4 - dichlorophenyl) -1, 1 - dimethylurea (B); 3 - (4 - chlorophenyl) -1, 1 - dimethylurea (C)] on the epoxy/dicyandiamide system were compared. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were utilized to study the reactivity and curing reaction kinetics of three epoxy/ icyandiamide/urea systems. It was showed that the best ratio for system A was 100:6:4 (Epoxy: dicyandiamide: urea A). The system needed 40 min to be cured completely at 130 ℃. The activation energy Ea for system A, B, C was 64.66, 71.68, 71.03 kJ/mol and the reaction order for the three systems was 0.897, 0.930 and 0.928, respectively. All the shear strengths of the three adhesive systems at room temperature were higher than 20 MPa, in which the system A provided the highest value of 24.98 MPa.

Key words: epoxy resin, dicyandiamide, urea derivatives, curing reaction kinetics