The role of nanodispersion on the fire performance of organoclay-polyamide nanocomposites

This work has investigated the importance of nanoscale dispersion upon the fire performance of Nylon-6 nanocomposites by characterising the role of the char layer and its formation in reducing peak heat release rate during combustion. To do this, a series of layered silicate nanocomposites systems using Nylon-6 were prepared using twin screw extrusion techniques at different levels of clay addition and different processing temperatures. This work has shown that the addition of layered silicates improves the peak heat release rate in a synergistic manner, by forming a tough char layer that prevents or hinders the transfer of combustible products into the gaseous phase. Differences in nanoscale dispersion of the clay as measured using transmission electron microscopy (TEM) correlated strongly with changes in fire performance according to cone calorimetry measurements. Corresponding changes in the thermal decomposition behaviour (thermogravimetric analysis) and microstructure and elemental composition of the char layer (SEM) were used to further understand the fire retardation mechanism in the condensed phase. Comparison of the rate of mass loss with the heat release rates and XRD of the char were further used to investigate the role of the char layer in improving fire performance.