Nanocomposites of polypropylene/polyamide 6 blends based on three different nanoclays: Thermal stability and flame retardancy

Abstract

The influence of various layered silicates: sepiolite (needle-like structure), halloysite (nanotube structure) or organomodified montmorillonite (lamellar structure) in combination with phosphorous flame retardants [ammonium polyphosphate (APP) and aluminum diethylphos-phinate (OP)] on the properties and morphologies of compatibilized PP/PA 6 blends has been investigated. Thermal degradation and fire retardancy of these blends were explored using TGA, cone calorimeter, pyrolysis flow combustion calorimeter (PCFC). Morphology of nanocomposites and residues as well of the chemical structure formed after cone calorimeter tests were investigated. The sepiolite/APP composition led to the better fire performance through the formation of a large amount of charred and expanded residue reinforced by the sepiolite fibres. The better compactness of this residue than that of the montmorillonite/APP one enables to account for the interest of sepiolite, whereas montmorillonite exerts the better fire retardant role, alone in the polymer blend.