Preparation and property characterization of halogen-free fire retardant ethylene-vinyl acetate copolymer foam composites

In order to obtain retardant ethylene-vinyl acetate (EVA) foam composites, two different compounded fire retardant consisting of expandable graphite-ammonium polyphosphate (EG-APP) and expandable graphite-ammonium polyphosphate-thermoplastic starch (EG-APP-TPS) were added to prepare alogen-free fire retardant EVA foam composites by process of molten blending and sulfuration foam. The EG-APP/EVA and EG-APP-TPS/EVA foam composites were characterized by limit oxygen index (LOI), vertical combustion (UL-94), thermal analysis mass spectrometry (TG-MASS) and scanning electron microscopy (SEM) test. The results demonstrate that the LOI of EG-APP/EVA foam composite is 28.1% and the flame retardant grade reaches to UL-94 V-1 at 30wt% total loading of EG and APP with mass ratio of 1:4.However, at 30wt% total loading of EG, APP and TPS with mass ratio of 1:4:1, LOI 29.3% and UL-94 V-0 rating are obtained. The results from TG-MASS and SEM tests show a good synergistic effect of EG, APP and TPS in solid and gas phase.