Rotational Molding of Polyamide-6 Nanocomposites with Improved Flame Retardancy

The aim of this work was to develop polyamide-6/ organic-modified montmorillonite (omMMT) nanocomposites for the production of hollow parts by rotational molding. Particular emphasis was placed on the niechanical and flame retardancy properties needed for the fabrication of vessels for flammable liquids. The morphology of the melt compounded nanocomposites, produced by melt compounding, was investigated by X-ray diffraction measurements (WAXD), and Transmission Electron Microscopy (TEM) showed an exfoliated structure. Rheological measurements were used in order to verify whether the viscosity of materials was adequate for rotational molding. While thermomechanical analysis has revealed that neat PA6 and its nanocomposites were not suitable for rotational molding, due to the very low thermal stability of the polymer, the addition of a thermal stabilizer, shifted the onset of degradation to higher temperatures, thus widening the processing window of both PA6 and PA6 nanocomposites. Large-scale vessel prototypes were obtained by rotational molding of thermo-stabilized PA6 and its nanocomposites, and samples extracted from the rotomolded parts were characterized with respect to physical and mechanical properties. It was found that the PA6 nanocomposites exhibited significant improvements at cone calorimeter tests in comparison with neat PA6.