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Global Innovation: Pure Wood 3D Printing!

2024-03-22 18:06

Natural wood, as the basic material for architecture, furniture, and building structures, has a history dating back thousands of years, and its forming process usually uses reduced material manufacturing technology. However, this method often generates a large amount of wood waste, which not only leads to low material utilization but also increases production costs. If 3D printing technology can be used to create complex wooden structures, a new possibility can be opened up, which will promote the upgrading and recycling of natural wood.

 

Recently, researchers from Rice University published an innovative study in the journal Scientific Progress, showcasing the enormous potential of using 3D printing technology to manufacture sustainable wood structures, providing a more environmentally friendly alternative than traditional manufacturing methods. By using direct ink writing (DIW) technology to produce complex wood structures, and then through heat treatment, these printed structures have visual, texture, odor, and macroscopic anisotropic properties, including their mechanical properties, which are extremely similar to natural wood.

This study utilized a special additive free water-based ink made from two basic components of natural wood - lignin and cellulose. This not only avoids the use of any adhesives or foreign polymers, but also eliminates the use of chemicals such as acetone when processing waste wood, further reducing the environmental burden. The manufacturing process of this ink fully utilizes a large amount of wood waste, such as sawdust and sawdust.

 

In order to achieve the best printing effect, the research team proposed a specific ink mixing ratio: 25% lignin, 37.5% CNF and CNC, and an appropriate amount of water. This mixture has a texture similar to clay and is very suitable for direct ink writing (DIW) 3D printing technology. Compared to 3D printed wood fibers with approximately 70% PLA content currently available on the market, the use of this new type of wood ink is more environmentally friendly and closer to the characteristics of natural wood.

 

The process of making and printing wood ink is relatively simple and direct, but to complete the conversion from wood ink clay to 3D shape, a series of specific freezing and heating steps are required. Firstly, the printed sample needs to be placed under dry ice for 30 minutes, and then freeze-dried at -85 degrees Celsius and 0.1 millibar pressure for 48 hours. Subsequently, the sample is subjected to heat treatment and placed in an oven preheated to 180 degrees Celsius for 20 minutes. If necessary, a hot pressing step is also added.

 

Although this wood based ink demonstrates sustainability in all manufacturing steps, energy intensive processes such as freeze-drying and heating are still required. Therefore, in order to have a more comprehensive understanding of the sustainability of this process, technical and economic analysis and lifecycle assessment are needed in the future. In addition, while expanding the process scale, further experimental research is needed on extrusion parameters, ink formulation and rheology, as well as the suspension limitations of complex building scale structures.
However, this technology of using nanoscale building blocks for 3D printing wood through DIW can pave the way for the recycling of wood, the implementation of complex building wood structures, and the development of mechanically robust and fully functional hybrid 3D printed wood structures.