Abstract
Studies on the influence of drying processes on cellulose nanofiber (CNF) aerogel performance has always been a great challenge. In this study, CNF aerogels were prepared via two different drying techniques. The CNF solution was prepared via existing chemical methods, and the resultant aerogel was fabricated through supercritical CO2 drying and liquid nitrogen freeze-drying techniques. The microstructure, shrinkage, specific surface area, pore volume, density, compression strength, and isothermal desorption curves of CNF aerogel were characterized. The aerogel obtained from the liquid nitrogen freeze-drying method showed a relatively higher shrinkage, higher compression strength, lower specific surface area, higher pore volume, and higher density. The N2 adsorption capacity and pore diameter of the aerogel obtained via the liquid nitrogen freeze-drying method were lower than the aerogel that underwent supercritical CO2 drying. However, the structures of CNF aerogels obtained from these two drying methods were extremely similar.
Highlights
Aerogel is a porous material obtained by replacing the liquid component of a gel with gas without changing the three-dimensional network structure or volume of the gel [1,2]
cellulose nanofiber (CNF) aerogels were prepared via the supercritical CO2 drying and liquid nitrogen freeze-drying techniques
The CNF aerogels obtained from liquid nitrogen freeze-drying showed excellent shrinkage, lower specific surface area, higher pore volume, and higher density
Summary
Aerogel is a porous material obtained by replacing the liquid component of a gel with gas without changing the three-dimensional network structure or volume of the gel [1,2]. Nanocellulose aerogel materials can be obtained by replacement of liquid solution in wet gel by air via supercritical CO2 drying, freeze-drying, and other technologies [18,19,20]. The freeze-dried hybrid aerogels shrunk and exhibited excellent dimensional stability and complete pore structure. They showed excellent electromagnetic interference resistance and electrical conductivity. Cellulose aerogels obtained by freeze-drying have good quality and low shrinkage. The supercritical CO2 drying and liquid nitrogen freeze-drying techniques were incorporated to prepare spherical CNF aerogels. The physical and chemical properties of the aerogel materials were studied (e.g., shrinkage, specific surface area, isothermal desorption curves, and microstructure) to compare the characteristics of the two drying methods. This study is expected to provide an effective reference for the preparation of high-performance cellulose nanofiber aerogel products
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