Estudi e identificació de materials polimers

At higher conversions (>80%), there was an inversion of this behaviour. Therefore, at the end of the nanocomposite curing, the epoxide groups were totally consumed whereas the amine conversion was about 87-92%. This can be explained by taking into consideration that the hardener is present in a slight excess.
The isothermal trials were used to determine the best kinetic model. Our experimental data presented poor adjustment when using the autocatalytic kinetic model whereas there was an excellent correlation when the first-order kinetic model and Avrami equation was employed.

In the first-order kinetics model, the traditional equations were modified by changing 1 by the asymptotic conversion reached at each temperature: m (epoxide groups) = 0.41, 0.93 and 1 for 120, 150 and 200ºC, respectively and m (primary amine groups) = 0.50, 0.66 and 0.83. The kinetic constants for the disappearance of epoxide and primary amine groups were quite similar when using these two kinetic models because of the n exponent (in Avrami equation) was found to be very close to 1.