Correlation analysis of heat flux and cone calorimeter test data of commercial flame-retardant ethylene-propylene-diene monomer (EPDM) rubber

Abstract

The effects of the heat flux on the thermal decomposition of the commercial flame-retardant ethylene-propylene-diene monomer rubber in a cone calorimeter with a piloted ignition were quantitatively investigated. Correlation analysis of the heat flux and various characteristic parameters, including the ignition time, the thermal thickness, the mass loss rate (MLR), the heat release rate (HRR) and the effective heat of combustion, was conducted. It was found that the transformed ignition time (1/t ig)0.55 and 1/t ig, the peak and average MLR, the first and second peak HRR, the HRR in the quasi-steady stage and the average HRR all increased linearly with the heat flux. The thermal thickness (δ P) decreased with the heat flux and was proportional to $$ \rho/\dot{q}^{\prime\prime} $$ . The specimens under the heat fluxes ≤35 kW m−2 behaved as thermally thin solids, while the thermal decomposition behavior of the specimens under the heat fluxes >35 kW m−2 may be characterized employing the thermally thick heating model. The flammability properties including the critical heat flux, the minimum heat flux, the ignition temperature, the heat of gasification and the heat of combustion, which were calculated theoretically based upon the correlations of the ignition time data, the MLR data and the HRR data with the heat flux, were in accordance with the experimental measured values.