High thermal stability and low flammability for Ethylene-Vinyl acetate Monomer/Ethylene-Propylene-Diene Monomer by incorporating macromolecular charring agent

The intumescent flame retardant (IFR) compounded with triazine charcoal-forming agent (CFA) and ammonium polyphosphate (APP) was applied to the flame-retardant modification of EVM/EPDM. The effect of APP-CFA on the flame-retardant performance of the composite was studied. The results showed that APP-CFA effectively enhanced the flame-retardant performance of EVM/EPDM. Compared with the control sample, when the APP–CFA ratio was 4:1, the limit oxygen index of EVM/EPDM with APP–CFA was up to 27.1%, which was increased by about 40%, and the average heat release rate was 110.1 kW/m², which was reduced by about 29%. Moreover, it passed the UL-94 V-0 test. TGA results showed that after the addition of APP/CFA, the amount of residue significantly increased. SEM test showed that the char layer formed by the composite containing APP/CFA during combustion was denser and more uniform. In addition, compared with the traditional intumescent flame-retardant ammonium polyphosphate–dipentaerythritol–melamine (APP-DPER-MN), the new flame-retardant APP–CFA has better flame-retardant and comprehensive performances.