Structure–Property Synergy in Novel Flexible Acrylonitrile Butadiene Rubber Foam‐Like Aerogels: Linking Thermo‐Physical Performance to Microstructure

Elastomeric foams are lightweight materials known for their excellent combination of elasticity, resilience, and thermal insulation properties, often exhibiting porosities. In this study, elastomeric foams based on acrylonitrile butadiene rubber (NBR) were synthesized using a unique processing technique to enhance their mechanical properties while retaining their superior flexibility and thermal insulation capabilities. Comprehensive characterization was carried out using rheometry, thermal and mechanical assessments, swelling analysis, and morphological investigations. When comparing the very high curing (VHC) and very low curing (VLC) formulations, the maximum torque (MH) increased from 24.7 dN·m (VLC) to 73.4 dN·m (VHC). Thermal analysis showed an increase in curing enthalpy from 701 to 1020 J/g, indicating higher crosslink network formation. The crosslink density ( V c ) ranged from 1.14 to 2.62 mol/m 3 . Microstructure imaging revealed porous structures without signs of capillary cracking, suggesting good structural stability. Ultimately, an analytical rectangular cube model was developed to estimate effective thermal conductivity and porosity. The model's predictions aligned well with experimental data, with the lowest thermal conductivity measured at 0.049 W·m −1 K 1 and porosity reaching up to 82.6%. This study presents a scalable, tunable approach for producing mechanically flexible, thermally efficient NBR‐based foams‐like aerogel, suitable for lightweight and durable insulation applications.