【摘要】 采用真空冷冻干燥法制备了聚甲醛纤维（POM）/纤维素纳米纤维（CNF）复合气凝胶，系统探讨了POM纤维长度对气凝胶结构与性能的影响。并向体系中引入不同质量百分含量的纳米二氧化硅（SiO₂），制备了POM/CNF/SiO₂复合气凝胶，并研究了其辐射冷却性能的变化。通过在晴朗天气下分别对比阳光直射与阴影环境中气凝胶样品的温度变化。结果表明，在阳光直射条件下，以1 mm长度POM纤维制备的POM/CNF气凝胶可实现最高8.7℃的亚环境降温效果，而加入SiO₂后的POM/CNF/SiO₂气凝胶降温幅度进一步提升，最高可达12.2℃；在阴影环境中，两者的降温幅度分别为2.5℃和1.6℃。此外，适量添加纳米SiO₂显著提高了材料的太阳反射率（最高达92.44%）和机械压缩性能，同时保持了较高的红外发射率（82.56%）和低热导率[0.048 W/（m·K）]。更多还原

【Abstract】 In this study,polyoxymethylene （POM）/cellulose nanofiber （CNF） composite aerogels were fabricated via vacuum freeze-drying,and the influence of fiber length on their structure and properties was systematically investigated.Nano-silica （SiO₂） was incorporated at varying mass percentages to produce POM/CNF/SiO₂ composite aerogels,and their radiative cooling performance was evaluated.Temperature variations of the aerogels were monitored under direct sunlight and shaded conditions on a clear day.Results indicated that the POM/CNF aerogel prepared with 1 mm fibers achieved a maximum sub-ambient cooling of 8.7℃under direct sunlight.With the addition of nano-SiO₂,the composite aerogel exhibited enhanced cooling performance,reaching a maximum temperature reduction of 12.2℃.Under shaded conditions,the temperature drops were 2.5 and 1.6℃ for the POM/CNF and POM/CNF/SiO₂ composite aerogels,respectively.Notably,the optimal incorporation of nano-SiO₂ significantly improved solar reflectance （up to 92.44%） and compressive strength while maintaining high infrared emissivity （82.56%） and low thermal conductivity[0.048 W/（m·K）].These findings indicate that POM-based composite aerogels exhibit exceptional radiative cooling performance and favorable mechanical properties,offering a viable strategy for energy-efficient cooling applications and the development of high-performance radiative cooling textiles.更多还原