Preparation of para-aramid aerogel and its pore structure regulation
WANG Wenzhao;CHEN Xuefei;DU Lei;School of Fashion Design & Engineering,Zhejiang Sci-Tech University;College of Textile Science and Engineering(International Institute of Silk),Zhejiang Sci-Tech University;Zhejiang Provincial Research Center of Fashion Engineering Technology,Zhejiang Sci-Tech University;
In order to overcome the problem of poor thermal insulation caused by easiness to collapse of aerogel skeleton under freeze-drying conditions, dimethyl sulfoxide(DMSO) and tetrabutylammonium fluoride(TBAF) solutions were prepared to dissolve para-aramid fibers. The pore structure of aerogel was regulated by altering the composition of tert-butyl alcohol/water replacement fluid, and para-aramid aerogels with excellent thermal insulation properties were prepared. The apparent morphology, microstructure, thermal stability, and thermal conductivity of the prepared aerogel were then characterized. The results showed that compared with the water exchange liquid, the addition of tert-butyl alcohol can change the growth morphology of ice crystals, making the interior of aerogel present a uniform three-dimensional reticulated pore structure and further improving the collapse of skeleton. With the increase of volume fraction of tert-butyl alcohol in the exchange liquid, the shrinkage rate of aerogel decreased first and then increased, and the thermal conductivity showed the same trend. When the volume fraction of tert-butyl alcohol was 50%, the shrinkage rate of aerogel was the minimum, and the apparent density was 0.021 g/cm~3. The specific surface area was up to 208.05 m~2/g, the thermal conductivity coefficient was 0.028 W/(m·K), and the thermal decomposition temperature was 560 ℃. The results of this study can provide a new idea for pore structure regulation of para-aramid aerogel by freeze-drying method.