Design and evaluation of lightweight <scp>EPDM</scp> composites using hydrophobic silica aerogel for thermal management systems

Abstract This study explores the development of lightweight thermal insulators based on ethylene propylene diene monomer (EPDM) reinforced with silica aerogel. Silica aerogel was synthesized via a sol–gel process and characterized using Brunauer–Emmett–Teller and scanning electron microscopy analyses, revealing its highly porous structure and low‐density properties, making it an ideal reinforcement material. The EPDM composites were formulated with different silica aerogel concentrations (10–30 phr) and evaluated for their mechanical, thermal and ablative properties using Tensile, thermogravimetric analysis/differential scanning calorimetry and an oxyacetylene flame, respectively. The incorporation of silica aerogel significantly enhanced the mechanical performance of the composites. The thermal conductivity of the composites was reduced significantly, demonstrating superior insulation properties over fumed silica‐filled EPDM. Thermogravimetric analysis indicated improved thermal stability, with a maximum degradation temperature of 474 °C for the 30 phr silica aerogel‐filled composite. Additionally, ablation tests confirmed that the char layer tenacity of the silica aerogel/EPDM composites was enhanced, and demonstrated superior resistance to high‐temperature environments, improved by the inclusion of Kevlar pulp, and achieved a linear ablation rate below 0.2 mm s −1 . These findings position silica aerogel as a promising reinforcement for EPDM‐based thermal insulators, striking a balance between low weight, enhanced mechanical strength and excellent thermal insulation. © 2025 Society of Chemical Industry.