The present work deals with the effect of the sonication amplitude and the mixing time on the mechanical and thermal properties of an epoxy (EP) resin modified with 1 wt% nanoclay. It was confirmed that the mechanical properties of the EP matrix were dependent on the dispersion of nanoclays which in turn are affected by the mixing parameters. At short mixing times, the impact strength (IS) increased with increasing amplitude. Maximum IS and flexural properties values were obtained with ultrasonic amplitude of 260 μm and a mixing time of 10 min. The effect of mixing time was more pronounced on the deflection temperature under load than the sonication amplitude. Moreover, it was shown that longer mixing times resulted in a smoother nanocomposite fracture surface with only few cracks. The fracture surfaces of the EP nanocomposites were rough with significant plastic deformations and several microcracks with nanoparticles embedded in the polymer matrix.
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