Synthesis and characterization of highly porous cellulose aerogels for textiles applications

Abstract

In this paper we present the synthesis and properties of ultra-light and porous cellulose aerogels in different forms: monoliths and fine spun fibers. The cellulose aerogel monoliths and fibers are prepared by dissolving microcrystalline cellulose (0.5-6 wt. %) in a hydrated calciumthiocyanate salt melt-Ca(SCN)2.4H2O at 110oC upon cooling the solution gels around 80°C. Washing the wet gels and regeneration of the cellulose in an ethanol bath followed by drying in an autoclave yields aerogels. The envelope densities of the samples were determined as in the range between 10-140 g/L. The microstructure was viewed with a SEM. The microstructure can be described as an open porous nano-felt with pore size ranging from 10 to 100 nm and fiber diameters of around 10-20 nm. The specific surface area and pore size distribution with nitrogen adsorption were measured with a surface area of 150-230 m2/g. Furthermore compression tests were performed. The mechanical behavior is typical for a porous material: after onset of deformation there is a long plateau at almost constant stress. The aerogels exhibit a Poisson ratio of around zero