Combined effect of palygorskite and melamine polyphosphate on flame retardancy properties of polyamide 11 nanocomposites

Abstract : Pyrolysis and fire behaviour of palygorskite (Pal) fibrous clay (5 wt%) reinforced polyamide 11 nanocomposites prepared by melt compounding were investigated in combination with melamine polyphosphate (MPP). Palygorskite was modified by 3-amino-propyl-triethoxysilane (APTES). Thermal stability and combustion behaviour of the materials were studied by thermogravimetric analysis (TGA), pyrolysis combustion flow calorimeter (PCFC) and cone calorimeter. TGA data showed that MPP reduced the thermal stability of PA11 nanocomposites, whereas the addition of both unmodified and modified palygorskite improved this property. Further, the cone calorimeter and PCFC results indicated a significant decrease in the peak of heat release rate (pHRR) and the total heat release (THR) of PA11 nanocomposites. This also means that the PA11 combustion was strongly reduced in the presence of combined Pal with MPP, being however more pronounced for the modified palygorskite. The improved fire behaviour could be attributed to a synergistic effect between Pal and MPP.