Synergistic aspects of the combination of magnesium hydroxide and ammonium polyphosphate in flame retardancy of ethylene-vinyl acetate copolymer

In this work, flame retardancy of ethylene-vinyl acetate copolymer (EVA) is investigated incorporating Mg(OH)(2) (MDH) as flame retardant combined with ammonium polyphosphate (APP) as potential synergist It is shown that APP is a synergistic agent in EVA-MDH formulations in terms of LOI and cone calorimetry The interactions between APP and MDH are studied using Mg-25 and P-31 solid state NMR. The formation of magnesium phosphate stabilizing phosphorus in the system and it is proposed that the combination APP/MDH provides a physical/thermal barrier protecting the substrate, this barrier is constituted of magnesium phosphate glass and MgO-like ceramic The degradation of the polymeric matrix is slowed and the flow of flammable molecules which issue from the degradation of the polymer is reduced.