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    大尺寸超轻高弹聚酰亚胺纳米纤维气凝胶的制备与性能

    Preparation and Properties of Large-Size Ultra-Light Super-Elastic Polyimide Nano-Fiber Aerogel

    • 摘要: 采用优化的模板冻干法在不同冷冻温度(−50,−20,0 ℃)下制备聚酰亚胺(PI)纳米纤维质量分数为0.3%~0.7%的大尺寸PI纳米纤维气凝胶,研究了气凝胶的微观结构、导热性能、力学性能、介电性能以及吸声性能。结果表明:制备的PI纳米纤维气凝胶最大尺寸可达50 cm×50 cm×1 cm;−20 ℃冷冻温度下制备的PI纳米纤维气凝胶纤维孔洞尺寸更小,纤维分布更均匀;不同PI质量分数下,PI纳米纤维气凝胶的密度在(3~7)×10−3 g·cm−3,导热系数在0.023 6~0.031 0 W·m-1·K-1,最大压缩应变大于90%,线性阶段弹性模量在1~3 kPa,介电常数在1 MHz处最低可达2.65,4 000~6 400 Hz频段下的平均吸声系数可达0.86。制备的PI纳米纤维气凝胶具有超轻质与低导热、良好柔韧性与回弹性、低介电与高吸声性等优点。

       

      Abstract: Polyimide (PI) nanofiber aerogels with mass fraction of 0.3%‒0.7% were prepared by optimized template freeze-drying method at different freezing temperatures (−50, −20, 0℃). The microstructure, thermal conductivity, mechanical properties, dielectric properties and sound absorption properties of the aerogels were investigated. The results show that the maximum size of PI nano-fiber aerogel could reach 50 cm×50 cm×1 cm. The pores of PI nano-fiber aerogel fibers prepared at −20 ℃ were smaller and the fiber distribution was more uniform. Under different PI mass fractions, the density of PI nano-fiber aerogel was (3~7)×10−3 g·cm−3, and the thermal conductivity was in the range of 0.023‒0.029 W·m−1·K−1, the maximum compressive strain was greater than 90%, the linear elastic modulus was in the range of 1~3 kPa, the lowest dielectric constant at 1 MHz was 2.65, and the average acoustic absorption coefficient at 4 000‒6 400 Hz was 0.86. The PI nanofiber aerogel had the advantages of ultra-light weight, low thermal conductivity, good flexibility and resilience, low dielectric and high sound absorption.

       

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