Characterization of thermal decomposition behavior of commercial flame-retardant ethylene-propylene-diene monomer (EPDM) rubber

The thermal decomposition behavior of the commercial flame-retardant ethylene-propylene-diene monomer (EPDM) rubber was studied employing cone calorimeter and simultaneous thermogravimetry (TG)-differential scanning calorimetry (DSC). Significant influence of the external heat flux on the thermal decomposition behavior of the commercial flame-retardant EPDM rubber was characterized with the measurement of various parameters, including the visual observation, the ignition time, the mass loss, the mass loss rate, the heat release rate and the effective heat of combustion employing cone calorimeter. Three different decomposition regions of the commercial flame-retardant EPDM rubber may be identified according to the applied external heat flux employing cone calorimeter: (1) region 1 (external heat flux ≤35 kW m;) with well exertion of effectiveness of fire retardants to the EPDM rubber; (2) region 2 (35 kW m <external heat flux ≤ 45 kW m^-2) with gradual loss of effectiveness of fire retardants to the EPDM rubber; and (3) region 3 (external heat flux >45 kW m^-2) with little effectiveness of fire retardants to the EPDM rubber. Six thermal decomposition stages of the commercial flame-retardant EPDM rubber were noted in both of region 2 and 3. However, merely four thermal decomposition stages were demonstrated in region 1. Similar thermal decomposition behaviors of the commercial flame-retardant EPDM rubber to those of cone calorimeter experiments were examined in the TG-DSC tests, thus validating the cone calorimeter experimental results. The present study may be of practical use in fire safety design of the underground rail transportation systems.