Ultrasound Assisted Development of Structure and Properties of Polyamide 6/Montmorillonite Nanocomposites

In this paper, polyamide 6/montmorillonite nanocomposites (PA6CNs) were prepared via conventional and an ultrasonic extrusion technology developed in our laboratory. The structure and morphology of montmorillonite dispersed in conventional and ultrasonicated PA6CNs were studied by x‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The experimental results gained by XRD, differential scanning calorimetry (DSC), and polarizing optical microscopy (POM) showed that the dispersed morphology of montmorillonite plays an important role in the crystalline form, nucleation rate, crystallization temperature, crystallinity, and spherulite size of PA6 crystals. The ductility of conventional PA6CNs decreases with the addition of montmorillonite because of the presence of large, stacked montmorillonite particles. Compared with the conventional PA6CNs, the elongation at break and impact strength of the ultrasonicated PA6CN increase greatly due to the improved dispersion of montmorillonite and decreased size of spherulites, while also showing the higher yield strength. Thermogravimetric analysis (TGA) revealed a decrease in thermal stability of conventional PA6CNs, with the introduction of ultrasound further accelerating thermal decomposition. A possible explanation for the observed decrease in polymer thermal stability on ultrasonic treatment is provided.