Thermal degradation and stability of epoxy nanocomposites: Influence of montmorillonite content and cure temperature

The thermal behaviour and stability of epoxy nanocomposites were studied by thermogravimetric analysis (TGA). The nanocomposites consisted of a trifunctional epoxy resin, a hardener containing reactive primary amine groups and clay nanoparticles (i.e. montmorillonite), previously treated with octadecyl ammonium. Three levels of nanoclay content (0, 5 and 10%) and three temperature levels (120, 150 and 200 °C) were used. The exfoliation of nanoparticles within the material was analyzed by X-ray diffraction (XRD). The cure conversion was determined by Fourier transform infrared (FTIR) spectroscopy by selecting the suitable band for epoxide functional groups. The study demonstrated that the nanoclay greatly accelerates the cure, at the different cure temperatures studied. Finally, the thermal stability of the various nanocomposites was established by calculating various characteristic temperatures from thermograms as well as conversion and conversion derivative at maximum decomposition rate. The collisions between resin molecules, which are trapped within the nanoclay galleries, were less effective because they were protected against thermal degradation by the galleries. However, once the collision was effective, the thermal activation occurred more readily.