Preparation and Properties of Exfoliated Vermiculite-Polyamide 6 Nanocomposite

Ion-exchange treatment of natural vermiculite (VER) with dodecylammonium (DDA) ions and subsequent preparation of a polyamide 6 (PA6) based nanocomposite was conducted to investigate the potential suitability of VER for use in polymer nanocomposites. In order to investigate the ion-exchange behavior, ground VER powder and DDA were treated at 60°C for 12 h, in which time the intercalation reaction was completed. DDA intercalation was rapid and complete for VER even in dilute DDA solution (0.5 mass%) at a low suspension VER concentration of 1 mass%. The VER-PA6 nanocomposite was formed via exfoliation of a DDA modified VER (DDAVER) layer. DDAVER was melt-kneaded with PA6 in a twin-screw extruder at 260°C. The morphology of the nanocomposite was characterized using X-ray diffraction and transmission electron microscopy. Measurements of the mechanical properties and methanol permeability were also carried out. The DDAVER-PA6 nanocomposite exhibits a high degree of VER exfoliation and the rigidity and gas barrier properties also appear to reflect the nanocomposite morphology. Addition of a small amount of DDAVER with 3 mass% sili- cate was sufficient to improve the rigidity, heat resistance and barrier properties of the nanocomposite.