Influence of radiation-crosslinking on flame retarded polymer materials-How crosslinking disrupts the barrier effect

Rodolphe Sonnier (1) , Anne-Sophie Caro-Bretelle (1) , Loic Dumazert (1) , Marc Longerey (1) , Belkacem Otazaghine (1)

1 C2MA - Centre des Matériaux des Mines d'Alès

Fire behavior of flame retardant-free and flame retarded PP/PA6 blends was studied using pyrolysis-combustion flow calorimeter, cone calorimeter and epiradiator equipped with infrared camera and pyrometer. Blends were previously gamma-irradiated in presence of crosslinking agents at various doses (up to 100 kGy) in order to assess the influence of irradiation crosslinking on flame retardancy. Cross linked specimens exhibit a solid-like behavior under high temperature gradient in cone calorimeter and then distort considerably. The influence of such a behavior depends on the material properties. When the flame retardancy is provided by heat shielding effect, heat distortion disrupts the top protective layer leading to a substantial increase of peak of heat release rate (pHRR). The barrier layer is no longer able to prevent the heat transfer to the underlying condensed phase. In other cases (flame retardant-free blends or flame retardancy provided by other effects than heat shielding), heat distortion has negligible influence on heat release rate curves in cone calorimeter tests.

Mots clés: Flame retardancy; Barrier effect; Heat shielding; Heat distortion

Domaines: Polymères; Radiochimie; Matériaux

Rodolphe Sonnier, Anne-Sophie Caro-Bretelle, Loic Dumazert, Marc Longerey, Belkacem Otazaghine. Influence of radiation-crosslinking on flame retarded polymer materials-How crosslinking disrupts the barrier effect. Radiation Physics and Chemistry, 2015, 106, pp.278-288. ⟨10.1016/j.radphyschem.2014.08.012⟩. ⟨hal-02914238⟩