Flammability Characterization and Effects of Magnesium Oxide in Halogen-free Flame-retardant EVA Blends

摘要

The effects of magnesium oxide(Mg O) on the flame retardant performance of intumescent systems based on ammonium polyphosphate(APP) and pentaerythritol(PER) in ethylene vinyl acetate copolymer(EVA) were studied. The results showed that Mg O affects both the quality and quantity of residual char. There is an optimal value for the loading amount of Mg O. More or less Mg O loading may cause the formation of defective char layers and worsen the flame retardancy of EVA. According to the results of limiting oxygen index(LOI), vertical flammability test(UL94 rating) and cone calorimetry(CONE), the best flame retardancy with a strong and well intumescent char is obtained from the sample with 1 wt% of Mg O, which has the highest LOI value of 27.9, UL94 rating of V-0 and the lowest peak heat release rate of 242 k W·m?2.