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<p>In aerogel production, a specialized drying process is essential to replace the solvent inside the pores with air while maintaining the silica alcogel network. Among drying methods, supercritical carbon dioxide (scCO<sub>2</sub>) drying and freeze-drying (FD) are commonly used, but their effects on pore structure and performance differ significantly. This study compares the effects of scCO<sub>2</sub> drying and FD on the microstructure and performance of silica aerogel composites. Supercritical drying, performed at low-temperature (40&#xa0;°C) and low-pressure (100 bar), beyond the CO<sub>2</sub> critical point, enabled a safer and more efficient process. Small angle x-ray scattering confirmed that scCO<sub>2</sub>-dried aerogels exhibited more complex and uniform pore structures, demonstrating enhanced thermal insulation through the "tortuous path effect" and "Knudsen effect." In contrast, FD samples showed partial pore collapse and inferior physical performance. Aerogels-coated melt-blown polypropylene (PP) nonwovens prepared via scCO<sub>2</sub> drying exhibited significantly improved mechanical performance, with tensile strength increasing from 0.84&#xa0;MPa to 2.15&#xa0;MPa (~2.5 times), and compression strength from 0.08 to 0.22&#xa0;MPa (~2.7 times). Thermogravimetric analysis (TGA) showed enhanced thermal stability, with weight loss reduced to 53.0% compared to 99.4% for general PP nonwoven. These improvements result from the synergistic effect of the aerogel porous thermal insulation properties and the physical properties of the PP nonwoven. The results underscore the critical role of drying method selection in aerogel composites processing and suggest that scCO<sub>2</sub> drying offers a superior strategy for developing high-performance thermal insulation materials for electric vehicle battery packs and aerospace systems.</p>

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Enhanced properties of silica aerogels/melt-blown nonwoven composites: a comparative study of supercritical CO2 and freeze-drying methods

  • 期刊论文

  • 发表日期：

    2025年7月22日

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  • Hongyeon Lee,
  • Junseok Song,
  • Chul B. Park,
  • Sangho Lee,
  • Jong Dae Jang,
  • Jaseung Koo

摘要

In aerogel production, a specialized drying process is essential to replace the solvent inside the pores with air while maintaining the silica alcogel network. Among drying methods, supercritical carbon dioxide (scCO2) drying and freeze-drying (FD) are commonly used, but their effects on pore structure and performance differ significantly. This study compares the effects of scCO2 drying and FD on the microstructure and performance of silica aerogel composites. Supercritical drying, performed at low-temperature (40 °C) and low-pressure (100 bar), beyond the CO2 critical point, enabled a safer and more efficient process. Small angle x-ray scattering confirmed that scCO2-dried aerogels exhibited more complex and uniform pore structures, demonstrating enhanced thermal insulation through the "tortuous path effect" and "Knudsen effect." In contrast, FD samples showed partial pore collapse and inferior physical performance. Aerogels-coated melt-blown polypropylene (PP) nonwovens prepared via scCO2 drying exhibited significantly improved mechanical performance, with tensile strength increasing from 0.84 MPa to 2.15 MPa (~2.5 times), and compression strength from 0.08 to 0.22 MPa (~2.7 times). Thermogravimetric analysis (TGA) showed enhanced thermal stability, with weight loss reduced to 53.0% compared to 99.4% for general PP nonwoven. These improvements result from the synergistic effect of the aerogel porous thermal insulation properties and the physical properties of the PP nonwoven. The results underscore the critical role of drying method selection in aerogel composites processing and suggest that scCO2 drying offers a superior strategy for developing high-performance thermal insulation materials for electric vehicle battery packs and aerospace systems.