Influence of ammonium polyphosphate on flame-retardant behavior and smoke suppression property of EVA/magnesium hydroxide composites

Abstract

ABSTRACTTo overcome the flammability and smoke generation of EVA, samples with different mass fraction of magnesium hydroxide (MH) and ammonium polyphosphate (APP), have been prepared by internal mixer and cured by compression molded. The fire characteristics including smoke and heat production of EVA composites were studied by cone calorimeter test (CCT), limiting oxygen index test, UL-94 test, scanning electron microscopy, and thermogravimetric (TG) analysis, respectively. For the sample EVA5 loading 10.0 mass% APP and 40.0 mass% MH, the LOI value can be increased to the value of 31.1 and reach V-0 level. The CCT test showed that APP and MH could significantly improve the fire safety of EVA. Remarkably, the peak of heat release rate, the peak of smoke production rate, and total smoke release for EVA5 were decreased by 75.4%, 88.1% and 70.8% compared with pure EVA, respectively. TG test showed that APP promoted the char formation in the degradation process of EVA; as a result, the residual carbon was increased. The results indicated that APP combined with MH could facilitate the formation of the rigid intumescent char and obviously enhance the flame retardancy, smoke suppression and thermal stability of the EVA matrix.