Category: Transient Plane Source
Author(s): Barbara Milow, Bjorn Schulz, Ilknur Karadagli, Lorenz Ratke, Maria Schestakow, Thomas Gries
Keywords: aerogel fiber, cellulose aerogel, salt hydrate melt, supercritical drying, thermal conductivity, transient plane source, transient plane source (tps) method, twin screw extrusion
Abstract: This study outlines the preparation method and properties of thin extruded cellulose aerogel fibers and monolithic pieces. Microcrystalline cellulose was combined with a hydrated calciumthiocyanate salt melt to form a gel at 80˚C. In order to obtain fine, homogenous, wet cellulose filaments, twin screw extrusion experiments were performed. Cellulose aerogel filaments were yielded once the gels were washed and coagulated in an ethanol solution, and had undergone supercritical drying with CO2. The properties of these cellulose aerogel fibers were then characterized by thermal conductivity measurements, BET analysis, tensile and compression tests and scanning electron microscopy. The pore sizes of these microstructures ranged from 10 to 100nm, while the fibril diameters ranged from 10 to 25nm. The fibers also displayed thermal conductivity ratings between 0.04 and 0.075 W/m.K. Other factors were noted during this process; the higher the spinning temperature, the higher the surface area of the fiber, furthermore, the higher the cellulose content, the better the strength of the fiber.This study outlines the preparation method and properties of thin extruded cellulose aerogel fibers and monoliths. Microcrystalline cellulose was combined with a hydrated calciumthiocyanate salt melt to form a gel at 80˚C. In order to obtain fine, homogenous, wet cellulose filaments, twin screw extrusion experiments were performed. Cellulose aerogel filaments were yielded once the gels were washed and coagulated in an ethanol solution, and had undergone supercritical drying with CO2. The properties of these cellulose aerogel fibers were then characterized by thermal conductivity measurements, BET analysis, tensile and compression tests and scanning electron microscopy. The pore sizes of these microstructures ranged from 10 to 100nm, while the fibril diameters ranged from 10 to 25nm. The fibers also displayed thermal conductivity ratings between 0.04 and 0.075 W/m.K. Other factors were noted during this process; the higher the spinning temperature, the higher the surface area of the fiber, furthermore, the higher the cellulose content, the better the strength of the fiber.
Reference: The Journal of Supercritical Fluids, 106 (2015) 105–114
DOI: 10.1016/j.supflu.2015.06.011