The thermal decomposition behavior and kinetics of epoxy resins cured with a novel phthalide-containing aromatic diamine

The thermal decomposition behaviors and kinetics of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured by a novel phthalide-containing aromatic diamine (BAPP), were studied by thermal gravimetric analysis (TGA) technique in comparison with these of epoxy systems cured by 4,4′-diaminodiphenylsulfone (DDS) and equimolar mixture of DDS/BAPP, respectively. The initial decomposition temperature (Tinitial) and integral procedure decomposition temperature (IPDT) were used to evaluate the thermal stability of cured epoxy resins. Tinitial values are reduced with increasing BAPP content, while IPDT results show the cured DGEBA/BAPP system has the highest inherent thermal stability. The microstructure morphology of charred products, derived from the thermal decomposition of the cured epoxy networks, were characterized by scanning electron microscope (SEM). The decomposition kinetics was investigated by isoconversional approach and the activation energy (Ea) calculated by Starink equation exhibits different dependence on conversion (α) for three epoxy systems. Truncated Sestak-Berggren model was used to describe the thermal decomposition mechanism, and the result shows a good agreement between the experimental data and the theoretical model.