Dielectric response of various partially cured epoxy nanocomposites

The purpose of this work is to demonstrate the post-treatment importance using dielectric measurements on nanocomposites. During this post-treatment which is the application of heat over time, crosslinking completes and ageing sets in. Both effects usually take place in the same time. Besides the expected differences between the filled and unfilled epoxy samples, the influence of silane coupling agents and the use of ultrasonic waves on the clay was demonstrated. Since the samples used in the experiment were unusually soft, supposedly because of the insufficient initial curing (4h at 100°C), a total of 38 h of heat treatment was applied, after which an improvement of the mechanical rigidity was noticed. This heat treatment was also considered extremely useful in order to remove humidity from the samples volume. Comparing the results obtained for two samples, with and without the 38h of post treatment, the treated sample was found to have a more stable dielectric response at 20°C.