对位芳纶气凝胶粉体的制备与性能研究

以对位芳纶纳米纤维(PANF)水凝胶为原料，将冻凝胶粉碎法与冷冻干燥法相结合，制备出PANF气凝胶粉体。系统研究了对位芳纶气凝胶粉体的微观结构及性能参数，以及制备条件对产物形貌的影响，并初步探究了其应用。结果表明，液氮冷冻制备的PANF气凝胶粉体具有多孔结构，松装密度约为17.0 kg?m^-3，孔隙率约为98.8%，BET比表面积可达126.30 m²?g^-1。PANF气凝胶粉体的耐热性优异，在氮气气氛下500℃前几乎无分解；热导率较低，约为0.03 W?m^-1·K^-1。气凝胶粉体具有吸附罗丹明B等染料的特征，同时可作为纳米填充材料增强聚氨酯乳胶膜等聚合物材料的硬度，其低热导率表明其有望应用于绝热领域。

Preparation and performance of para-aramid aerogel powders

Using para-aramid nanofiber (PANF) hydrogel as raw material, the cryogel crushing method and freeze-drying method are combined together to prepare PANF aerogel powder. The microstructure and performance parameters of para-aramid aerogel powder and the influence of preparation conditions on the morphology of the product were systematically studied, and its application was preliminarily explored. The results showed that the aerogel powders have a porous structure. The apparent density, porosity, and Brunauer-Emmett-Teller surface aerogel area are about 17.0 kg?m^-3, 98.8% and 126.30 m²?g^-1, respectively. The thermal stability of aerogel powders is excellent and almost no decomposition occurs before 500°C under nitrogen atmosphere. The thermal conductivity of aerogel powder is as low as 0.03 W?m^-1·K^-1. The aerogel powders can be utilized for the adsorption of some kinds of dyes, such as Rhodamine B. Furthermore, the aerogel powders can be used as nanofiller to improve the mechanical performance of some kinds of polymers, such as the hardness of polyurethane latex film. The low thermal conductivity indicated that the aerogel powder might be applied in the area of thermal insulation.