Oriented clay-induced anisotropic crystalline morphology in poly(ethylene naphthalate)/clay nanocomposites and its impact on mechanical properties

The hierarchical structure developed in an injection-molded poly(ethylene naphthalate) (PEN)/clay nanocomposite, and its impact on the reinforcement of the nanocomposite are investigated. Wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) show that the clay sheets tend to orient parallel to the largest face of the molded sample. SAXS further provides evidence that upon annealing, this preferred orientation of clay induces an anisotropic crystalline morphology in the PEN matrix, where there are more secondary lamellae aligned parallel to the clay basal planes. Such lamellar organization of PEN works synergistically with the oriented clay phase in stiffening the material along the flow direction, as confirmed by dynamic mechanical analysis (DMA) and nanoindentation.