The curing kinetics and thermal properties of epoxy resins cured by aromatic diamine with hetero-cyclic side chain structure

• The Ea values are first constant and then decrease gradually with the fractional conversion.
• The progress of the non-isothermal curing reaction of the novel epoxy resin follows the autocatalytic reaction model.
• The glass transition temperature of novel epoxy network is above 170 °C and the activation energy for glass transition is higher.
• The novel epoxy network exhibits a lower rate of weight loss and higher char yield.

The use of novel aromatic diamine containing phthalide structure (BAPP) as curing agent of diglycidylether of bisphenol A (DGEBA) epoxy resin has been studied. BAPP can react with epoxy monomers by an epoxy-amine condensation mechanism, which renders phthalide cardo incorporate into the network structure of the thermoset. The curing behavior and kinetics have been investigated by differential scanning calorimetry (DSC) and the kinetic analysis of non-isothermal cure shows that autocatalytic model is suitable to describe the cure mechanism. The thermal–mechanical properties have been determined with dynamic mechanical analysis (DMA) and the activation energies for relaxation were calculated according to the Arrhenius law. Thermogravimetric analysis exhibits a lower initial decomposition temperature, decreased rate of decomposition and higher char yield compared with DGEBA cured with commercially available 4,4′-diaminodiphenylsulfone (DDS).