Aalto University School of Engineering, Department of Mechanical Engineering, Aalto, 00076, Finland.
VTT Technical Research Centre of Finland Ltd, Espoo, 02044, Finland.
Sci Rep. 2019 Mar 7;9(1):3822. doi: 10.1038/s41598-019-40469-x.
The aim of the present study was to investigate the additive manufacturing process for high consistency nanocellulose. Unlike thermoformable plastics, wood derived nanocelluloses are typically processed as aqueous dispersions because they are not melt-processable on their own. The ability to use nanocellulose directly in additive manufacturing broadens the possibilities regarding usable raw materials and achievable properties thereof. Modern additive manufacturing systems are capable of depositing nanocellulose with micrometer precision, which enables the printing of accurate three-dimensional wet structures. Typically, these wet structures are produced from dilute aqueous fibrillar dispersions. As a consequence of the high water content, the structures deform and shrink during drying unless the constructs are freeze-dried. While freeze-drying preserves the geometry, it results in high porosity which manifests as poor mechanical and barrier properties. Herein, we study an additive manufacturing process for high consistency enzymatically fibrillated cellulose nanofibers in terms of printability, shape retention, structure, and mechanical properties. Particular emphasis is placed on quantitative shape analysis based on 3D scanning, point cloud analysis, and x-ray microtomography. Despite substantial volumetric as well as anisotropic deformation, we demonstrate repeatability of the printed construct and its properties.
本研究的目的是探索高浓度纳米纤维素的增材制造工艺。与可热成型的塑料不同，木材衍生的纳米纤维素通常作为水基分散体进行加工，因为它们本身不能熔融加工。能够直接将纳米纤维素用于增材制造，拓宽了可用原材料的可能性和可实现的性能。现代增材制造系统能够以微米级的精度沉积纳米纤维素，从而能够打印出精确的三维湿结构。通常，这些湿结构是由稀的纤维状分散体制造的。由于水含量高，结构在干燥过程中会变形和收缩，除非构建物经过冷冻干燥。虽然冷冻干燥可以保持结构的几何形状，但会导致高孔隙率，表现为较差的机械和阻隔性能。在此，我们研究了一种高浓度酶法原纤化纤维素纳米纤维的增材制造工艺，包括可印刷性、形状保持、结构和机械性能。特别强调了基于 3D 扫描、点云分析和 X 射线微断层扫描的定量形状分析。尽管存在大量的体积和各向异性变形，但我们证明了打印结构及其性能的可重复性。
