Combustion behavior of polypropylene/polyamide66/clay nanocomposites

Abstract

The addition of treated nanoclay as the reinforcement agent modifies the melt behavior of PP/PA66 nanocomposites, but also profoundly decreases the burning rate of reinforced formulations. To modify the flammability of PP/PA66 nanocomposites, various amounts (0–6 wt%) of treated nanoclay were added to improve the fire performance of PP/PA66 nanocomposites. Horizontal flame test according UL94 was used to evaluate the fire performance of the reinforced formulations, and the results proved that the addition of more than 2 wt% treated nanoclay lead the improvements in flame retardancy through the reduced burning rate. The melt behavior of PP/PA66/Nanoclay nanocomposites was also investigated. It is proposed that, in the presence of clay, the combustion surface changed to a compact carbonaceous–silicate structure. When the clay content was 4–6 wt%, the layered silicates became enriched on part of the surface and formed an island-like structure; the islands displayed a loose cinder structure with much higher silicon content, in contrast to a surface with low silicon content in the surrounding polymers substrate. As the clay content continued to increase, the char covered most of the combustion surface and more clay accumulated on the burning surface. In addition, the clay particles promoted the formation of the carbonaceous–silicate structure. The melt behavior of the PP/PA66 nanocomposites was affected with increasing addition of clay