Study on the thermal insulation and flame-retardant properties of starch-based modified aerogels and their microscopic kinetic mechanisms.

Starch aerogels are green and sustainable bio-based materials with advantages such as low cost. However, their intrinsically poor flame retardancy and thermal insulation severely limit large-scale applications, highlighting the need for effective modification strategies. In this study, a starch-based composite aerogel (PA-M/PS) was fabricated from pea starch (PS) through PA crosslinking and MEL incorporation using a sol-gel process followed by freeze-drying. The incorporation of PA and MEL significantly improved flame retardancy while optimizing the porous structure for enhanced thermal insulation. The PA-M/PS aerogel exhibited a specific surface area of 27.48 m2/g, and its average pore diameter decreased from 10.72 nm to 2.86-9.57 nm. When the heating surface reached 234.5 °C, the backside temperature remained at only 93.5 °C. The thermal conductivity decreased to 0.157 W/(m·K), representing a 55.3% reduction compared with pristine PS. The modified aerogel also achieved self-extinguishing behavior after flame removal, with the peak heat release rate (pHRR) reduced to 184.8 W/g. The 4-PA-M/PS sample exhibited a compressive strength of 1.49 MPa and an equivalent tangent elastic modulus of 43.34 MPa, representing increases of approximately 89% and 19%, respectively, over pristine PS. Molecular dynamics simulations further revealed that the synergistic effects of PA and MEL suppressed gas-phase heat transfer by densifying the pore structure and enhancing pore-wall polarity, providing a molecular-level explanation for the improved thermal insulation performance.