The activation energy associated with the glass transition relaxation of an epoxy system has been determined by using the
three-point bending clamp provided in the recently introduced TA Instruments DMA 2980 dynamic mechanical analyzer. A mathematical
expression showing the dependency of modulus measurements on the sample properties and test conditions has also been derived.
The experimental results showed that the evaluation of activation energy is affected by the heating rate and test frequency,
as well as the criterion by which the glass transition temperature (Tg) is established. It has been found that the activation energy based on the loss tangent (tanδ) peak is more reliable than
on the loss modulus (E2) peak, as long as the dynamic test conditions do not cause excessive thermal lags.