Influence of Intumescent Flame Retardant NP430 on Flame Retardancy of EPDM

The EPDM was filled with intumescent flame retardant(IFR) NP430,and its flame retardancy was investigated.The results showed that,the flame retardancy of EPDM with NP430 was good,and addition of acid source such as ethylene vinyl acetate(EVA) and carbon source such as high styrene(HS) resin provided synergisitic effect on the flame retardancy of EPDM.When EPDM/EVA/HS blend ratio was 80/8.6/11.4,and the addition level of IFR NP430 was 90 phr,the limited oxygen index of EPDM could reach 47.6.The flame retardancy of EPDM was significantly reduced by addition of paraffin oil,but the intumescence during burning was not affected.Organic additives such as zinc dimethacrylate and phenolic resin only had a little effect on the flame retardancy of EPDM.Addition of inorganic additives such as carbon black,silica,calcium carbonate and expanded graphite led to rapid escape of gas formed by burning,which greatly reduced the effect of NP430 and flame retardancy of EPDM.