Cure kinetics and rheological properties of difunctional/trifunctional epoxy blend system thermoinitiated by cationic latent curing agent

Cure kinetics and rheological properties of diglycidylether of bisphenol A (DGEBA)/trimethylolpropane triglycidylether (TMP) epoxy blends mixed in varying proportion with 1 wt% N-benzylpyrazinium hexafluoroantimonate (BPH) as a thermal latent curing agent were investigated. Latent properties were investigated by measuring conversion as a function of reaction time using isothermal DSC method at 160 and 50°C. The cure activation energies (E_a) obtained by Kissinger method using dynamic DSC data were higher in DGEBA/TMP mixtures than in pure DGEBA. Rheological properties of the blend system were investigated under isothermal condition using a rheometer. Cross-linking activation energy (E_c) was also determined from the Arrhenius equation based on gel time and curing temperature. As a result, the cross-linking activation energy showed similar behavior with that of Kissinger method and gelation time decreased with increasing TMP content, which could be resulted from higher activated sites by trifunctional epoxide groups and low viscosity of TMP.