Flammability of Nanocomposites-Effects of the Shape of Nanoparticles
Nanocomposites based on three different shapes of nanoscale particles, sphere (silica), plate (clay), and tube (carbon nanotube), were prepared and the dispersion of the particles in the nanocomposites was confirmed by various techniques using TEM, SEM, optical microscopy, and XRD. Their flammability properties were measured by using a Cone calorimeter and a radiative gasification apparatus in nitrogen. The residues of these nanocomposites after the gasification test were collected and the shape and the structure of the residues were examined. The results show that the reduction in heat release rate is achieved in the order: carbon nanotubes, clay platelets, and silica spheres providing that these particles are well dispersed in the sample. It appears that the particles having higher aspect ratio tend to form an effective protective layer consisting of network-structured floccule which covers the entire sample surface without forming any cracks during burning. The formation of such a layer is critical to obtain low heat release rate from nanocomposites.