Molecular level dispersed cellulose solution was prepared by dissolving high cellulose content, chemically liberated wood-based fibers in a Dimethylacetamide/lithium chloride (DMAc/LiCl) mixture. This solution was used to prepare nm-smooth regenerated cellulose gel beads by precipitation in ethanol. The 3D network and porous structure within the formed wet cellulose bead were evaluated from SEM images of the bead after critical point drying (CPD). A more compact structure was found when the wet bead was dried under ambient conditions at room temperature. The size of the bead was changing during drying and this shrinking was recorded by USB microscopy. A constant contact angle was also observed for the beads during drying from the side view of the USB microscopy measurements. Besides the morphology from the SEM images, the internal structure of the wet bead and the structural evolution was investigated by in situ small angle X-ray scattering (SAXS) during drying.  From the SAXS measurements, two characteristic lengths were obtained to describe the internal structure in the wet bead. From the change of these two characteristic lengths during drying the drying process can be divided into three different steps.  These nm-smooth dried beads can be used as cellulose model system to evaluate what is occurring during the joint formation with contact adhesion experiments.<br/>

Internal structural evolution of regenerated cellulose beads during drying

2019 Spring National Meeting

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