In order to study the pyrolysis ablation process of ethylene propylene diene monomer (EPDM) insulator under thermal load

a variable thermal properties model

in which the thermal properties of aramid/EPDM insulator vary with temperature and time

was established based on pyrolysis kinetics

mass and heat transfer theory of porous media. The accuracy and reliability of the present model were verified by comparing with experimental results. Then numerical calculations for the ablation thermal response under thermal load were carried out. Results showed that at the initial stage of thermal loading

the surface of the material heated up rapidly. As the energy continued to transmit

the temperature advancement rate and the charring layer thickness reduced significantly

and the part of the material was still in their original state. The effect of temperature on the pyrolysis reaction rate presented an exponential trend. The closer to the surface reflected the faster reaction rate and vice versa. The variable thermal properties model has certain reference value for the ablation research of thermal insulation materials.