Experimental study of the thermal property evolution of EPDM during ablation for thermal protection applications

Ablative polymer materials are extensively utilized in the thermal protection applications owing to their elasticity, electrical insulation, gas tightness, and ablation resistance. Ethylene Propylene Diene Monomer (EPDM) is one of the promising ablative polymer materials due to their unique ablation resistance and favorable thermomechanical properties. To achieve precision in designing thermal protection structures, the thermal properties of EPDM are indispensable. Current research lacks accurate characterization of the thermal properties of EPDM under ablative conditions. Therefore, in this study, the thermal properties of EPDM elastomer were experimentally characterized before and after ablation. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were adopted to characterize thermal degradation profiles and specific heat capacity over the temperature range of 25 to 600 ℃. The thermal conductivity was measured using the 1D steady-state method on surface-ablated samples over 23–605 ℃ and the transient plane source (TPS) method on bulk-ablated samples over 27–483 ℃. The spectral emissivity of EPDM before and after ablation was determined through the energy balance calibration based on the Fourier transform spectrometer. Results indicate significant degradation and ablation of EPDM at elevated temperatures, accompanied by a decrease in its thermal properties. The underlying mechanisms governing these changes are discussed.