Critique of Dielectric Cure Monitoring in Epoxy Resins – Does the Method Work for Commercial Formulations?

Dielectric techniques can be used as an in situ monitor of resin cure. This study reports measurements on two commercial resin formulations and aims to establish the extent to which identifiable turning points in the dielectric behaviour are dependent of the formulation used. Complementary curometer and differential scanning calorimetry data are used to monitor the progress of cure and are compared with the dielectric data. System [A] is a simple epoxy amine system, whilst system [B] is a blend of both epoxy and amine resins. It is clear that without calibration of the dielectric data against other methods it is difficult to unambiguously derive absolute cure information on a system not previously studied. However, dielectric data does allow identification of the points at which gelation and vitrification occur and demonstrates its utility as an in situ monitoring method for the cure process.