We selected six different biomasses with contrasting properties (hemp core, pine bark, rice husk, rice husk ash, hibiscus, and spirulina). Ten powders, meeting the specifications for 3D printing, were generated using various technological approaches. Our research primarily aimed to understand how these production methods influenced the powders' properties. Each biomass was thoroughly characterized with the goal of correlating its physical and chemical attributes with their impact on the rheology and processability of the composite materials derived from them.
The research focused on three printing techniques: Paste Printing, Selective Laser Sintering (SLS), and Fused Deposition Modeling (FDM). In line with our goal of minimizing environmental impact, we chose 100% biodegradable matrices such as PHA and natural waxes. This approach leveraged the cutting-edge biotechnological expertise of our host institution, SCION. However, our observations indicated that while Paste Printing showed potential, it lacked efficiency for precision tasks, prompting us to focus more on SLS and FDM.
For SLS, we concentrated on developing a process to produce composite powders for printing, using PHA, natural wax, and vegetable powders. We found that the yield of the SLS powder production process is highly dependent on the properties of the lignocellulosic biomass, though no clear correlation emerged. In an effort to optimize this procedure, we collaborated with the DAGI group (Data and Geospatial Intelligence) at SCION to explore the potential application of machine learning tools for enhancing process parameters, even with a limited dataset. Currently, we have tested various algorithms, with promising results, and further work is ongoing.
Regarding Fused Deposition Modeling, our research highlighted that the properties of lignocellulosic biomass significantly enhance the rheological characteristics and printability of the composite materials. Although the exact parameters responsible for these improvements are not yet fully understood, it appears that lignin content could play a key role in optimizing the printing process.
Finally, the work also demonstrated that mechanosynthesis conducted in a ball mill enables the production of grafted powders with fluorophore and anthocyanin, which can be used as sensors to develop active biobased materials that respond to environmental changes, such as pH variations.
So far, the results have led to five research articles, seven presentations, two patents, and six outreach activities. These outcomes have significantly exceeded the initial plan outlined in the DoA. Three more scientific publications are in preparation, and three presentations are already planned for 2024 and 2025.
