Crystallization behavior of PA-6 clay nanocomposite hybrid

Polyamide-6 (PA-6)/clay (modified montmorillonite) hybrid was synthesized by melt blending at high shear stress. Al-27-NMR of solid state shows that the clay is not modified after melt blending. Using wide-line H-1-NMR and TEM, it is demonstrated that the nanocomposite exhibits mainly an exfoliated structure. It is shown that the modified montmorillonite induces the crystallization of PA-6 predominantly in gamma-form. The presence of clay in PA-6 increases the polymer crystallization temperature, and decreases its melting point. These phenomena show that a certain number of interactions develop near the reinforcing material, and that the latter plays a particular role of nucleating agent. However, the crystallization is not spherulitic and the assumption of macromolecular orientation in the vicinity of the clay is demonstrated by the observations carried out in DSC and AFM. These particular properties of orientation will have a particular importance on the mechanical behavior of the nanocomposite material. (C) 2002 Wiley Periodicals, Inc.