Kinetics of a sterically hindered amine‐cured epoxy resin system

Fourier transform infrared spectroscopy (FT‐IR) and torsional braid analysis (TBA) were used to study the reaction of an epoxy resin system cured with a sterically hindered amine. Isothermal torsional braid analysis showed the apparent activation energy to be approximately 42 kJ/mol. The reaction kinetics were also considered from the unreacted freshly mixed condition and a partially reacted “B‐staged” condition using infrared spectroscopy, The B‐staged condition is unreactive and stable at room temperature due to the quenching of the primary amine reaction by the glassy structure and the steric hindrance of the secondary amine reaction. Apparent activation energies for these two conditions were found to be 49.4 kJ/mol and 49.0 kJ/mol respectively. The storage life at room temperature of the B‐staged resin system is predicted to be at least three months based on extrapolation of the experimental kinetic data.