Flammability of EVA/IFR (APP/PER/ZB system) and EVA/IFR/synergist (CaCO3, NG,and EG) composites

Poly(ethylene‐co‐vinyl acetate)/intumescent flame retardant (ammonium polyphosphate/pentaerythritol/zinc borate system) composites‐EVA/IFR (APP/PER/ZB system) and EVA/IFR/Synergist [CaCO₃, natural graphite, or expanded graphite (EG)] composites have been prepared by melting compounding method. The flammability, the combustion process, the quantity of the residual chars, the morphology of the residual chars, and the thermal stability of the chars have been investigated by cone calorimeter, scanning electron microscopy and thermo gravimetric analysis. The results indicate that heat release rate (HRR), total heat released, and total smoke release (TSR) of EVA/IFR (IFR 30 phr) composite decrease to about 67.1, 78.2, and 64% of that of pure EVA, respectively. HRR, THR, and TSR of EVA/IFR/EG (IFR 9 phr, EG 1phr) composite decrease to about 62.1, 76.2, and 44% of that of pure EVA, respectively. The quantity, the thermal stability of residual chars and the char structure are discussed to find the reasons of the phenomenon above. It has been found that the flame retardant of EVA vulcanizates is improved and the fire jeopardizing is dramatically reduced due to the addition of IFR and synergist, which can give some advice to design formulations for practical applications as cable. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012