Microstructural and mechanical properties of cellulose aerogels

Abstract

The nanostructure of cellulose aerogels consists of nanofibrils that are interconnected in a three-dimensional (3-d) space. The properties of cellulose aerogels are influenced by their nanofibrillar network which necessitates the analysis of their porous nanostructure using computational reconstruction methods. These mechanically strong aerogels are synthesized from aqueous salt hydrate melts [1] and tensile and compressive tests are conducted to investigate their mechanical properties. Furthermore, the structural properties such as the bulk and skeletal densities and the pore-size distributions are described. These pore-size distributions are used to generate a 3-d random close packing of polydisperse spheres [2] where the volume distribution of the spheres adheres to the pore-size distribution of aerogels. Then, Laguerre Voronoi tessellations [3] are generated on these spheres to obtain an open-porous fibrillar network while retaining the initial pore-volume distribution and thus corresponding to the 3-d nanostructure of aerogels. To investigate the macroscopic mechanical properties of these aerogels based on the modelled nanostructure, the open-porous networks are imported into a finite-element program as representative volume elements (RVE). The elastic as well as the inelastic features are described and validated with corresponding experimental data. [1] Rege A., Schestakow M., Karadagli I., Ratke L., & Itskov M., Soft Matter, 12, 7079-7088, 2016 [2] Lubachevsky B. Z. & Stillinger F. H., Journal of Statistical Physics, 60(5), 561-583, 1990 [3] Imai H., Iri M., & Murota K., SIAM Journal on Computing, 14(1), 93105, 1985