Fabrication of Cellulose Hydrogel Objects Through 3D Printed Sacrificial Molds

Abstract

Effects of mold removal methods in fabrication of cellulose hydrogel objects were investigated in the present work. Cellulose was dissolved in 7 wt% NaOH/12 wt% urea aqueous solution and thermally gelled at 55 °C in three different mold materials, Acrylonitrile Butadiene Styrene (ABS) as a common 3D printing material, Solidscape™ wax, specifically designed as a 3D printing cast material, and sacrificial casting wax (Lost Wax), commonly used for casting. After completion of the gelling process, the molds were removed from the cellulose gel by using a solvent for the ABS mold and melting the waxes in hot water. At the same time, the solvent was extracted from the gel and the cellulose hydrogel regenerated. The results show that mold materials and their associated removal methods have a significant effect on the mechanical properties and microstructure of cellulose hydrogel and cause shrinkage. Larger pore sizes decreased the compression strength and modulus of cellulose hydrogels samples. A balance between the porosity and density for a cellulose hydrogel part must be established for the specific applications.