Lightweight and Mechanically Robust EPDM Foams for High Thermal Insulation and Moderate Ablative Resistance Via Constructing Cellular Char Layer

Ethylene propylene diene monomer (EPDM) foams have received considerable attention owing to their low weight, low thermal conductivity, and mechanical flexibility. However, their poor ablative resistance and low thermal stability make their use in severe conditions, such as the combustion chamber of a solid rocket motor, difficult. In this study, EPDM foams reinforced with aramid fibers (AFs) and carbon fibers (CFs) are prepared through a hot-pressing-induced foaming process. The effects of the fibers on the cellular structure, thermal stability, and mechanical, ablating, and insulating properties of the EPDM foams are investigated. The results show that the addition of CFs enhanced the thermal stability and mechanical properties of the EPDM foams, whereas the use of AFs lowered the thermal conductivity and ablation rate. In particular, when 2.5 phr (parts per hundred parts of rubber) AF and 2.5 phr CF are added, the linear ablation rate tested using oxyacetylene is 0.33 mm s(-1), and the back-face temperature is 53 degrees C, revealing a good balance in terms of ablative resistance and thermal insulation. Thus, the hybrid-fiber-reinforced EPDM foams possess several advantages, such as low weight, good thermal insulation, ablative resistance, and mechanical robustness, suggesting considerable potential for application in the aerospace industry.

Automated summary

EPDM foams reinforced with aramid fibers and carbon fibers showed enhanced thermal stability and ablative resistance, achieving a good balance between thermal stability and ablation rate. This hybrid-fiber-reinforced EPDM foam exhibits potential for applications in the aerospace industry due to its low weight, good thermal insulation, ablative resistance, and mechanical robustness.