A trifunctional active ester for curing DGEBA: synthesis, curing behavior, and properties of its cured product

A trifunctional active ester curing agent, triacetoxytriphenylmethane (TATPM), which was dissolvable in diglycidyl ether of bisphenol A (DGEBA), was prepared and characterized. Though TATPM/DGEBA mixture was too viscous to flow at room temperature, its viscosity rapidly declined to a very low level when heating above 120 °C, showing great processability. Accelerators 4-dimethylaminopyridine (DMAP), 2-methylimidazole (2MI), and tetrabutylammonium bromide (TBAB) were used to catalyze the reactions between TATPM and DGEBA. DMAP-catalyzed one reached T_peak and T_endset earlier, and showed higher conversion than 2MI and TBAB-catalyzed one, exhibiting superior accelerating effect. E_a and A of DMAP-catalyzed system were higher than that of 2MI-catalyzed system. Moreover, the properties of cured products depended on accelerator type, and DMAP-catalyzed one had the highest T_g, T_d5%, and T_d10%, lowest D_f, EQUATION and saturated water uptake, making DMAP a better accelerator than 2MI and TBAB. Meanwhile, TATPM cured epoxies showed higher T_d, lower D_k and D_f than that of phenolic compound THTPM cured epoxies, despite of its lower T_g.