ACS Appl Mater Interfaces. 2018 Aug 15;10(32):27407-27415. doi: 10.1021/acsami.8b04376. Epub 2018 Aug 2.
Cellulose nanofiber (CNF) aerogels offer excellent thermal insulation properties, but high flammability restricts their application. In this study, CNF aerogels were prepared by incorporating sodium bicarbonate (SBC), which effectively improved the fire retardancy without compromising the thermal conductivity of the aerogels, which was only 28 mW m K. The minimum burning velocity of flame-retardant aerogels was 0.20 cm s at 40 wt % of SBC, which is significantly lower compared to 5.84 cm s of pure CNF aerogels. At the threshold concentration of 20 wt % SBC, the flame-retardant aerogel demonstrated flameless pyrolysis along with enhanced char formation. SBC additionally provides control over the microporosity and morphology, due to the concentration-dependent formation of lamellar layers during the preparation of aerogels. Overall, this work describes an efficient method for preparing flame-retardant CNF aerogels that could lay the foundation for next-generation bio-based insulation materials.
纤维素纳米纤维（CNF）气凝胶具有优异的隔热性能，但高可燃性限制了它们的应用。在本研究中，通过加入碳酸氢钠（SBC）制备了 CNF 气凝胶，这有效地提高了阻燃性，同时又不会影响气凝胶的热导率，其热导率仅为 28 mW m K。在 SBC 含量为 40wt%时，阻燃气凝胶的最小燃烧速度为 0.20 cm s，与纯 CNF 气凝胶的 5.84 cm s 相比显著降低。在 SBC 阈值浓度为 20wt%时，阻燃气凝胶表现出无焰热解，同时增强了炭的形成。由于在制备气凝胶过程中，SBC 会形成层状结构，因此其浓度依赖性会对微孔隙率和形态产生影响。总的来说，这项工作描述了一种制备阻燃 CNF 气凝胶的有效方法，为下一代基于生物的隔热材料奠定了基础。
