Three-dimensional printing is renowned for its ability to produce complex geometries. By utilizing a pressure-driven additive manufacturing (AM) process called direct ink write (DIW) with polymer composite ink, it is possible to create parts with tailored internal microstructures that enhance surface area and particle-particle adsorption kinetics for water remediation applications. However, DIW of particle-filled systems faces challenges, particularly nozzle clogging. This paper explores the relationship between dispersion of aggregate size, torsional rheology, and the capacity to print relatively highly particle-filled systems. Various characterization methods, including torsional rheology, dynamic light scattering (DLS), and field emission scanning electron microscopy (FESEM) were employed utilizing a chitosan-graphene-titanium dioxide (CS-G-TiO2) polymer composite ink composed of TiO2 nanoparticles (1 wt.% to 25 wt.%), graphene (1 wt.%), and chitosan (5 wt.% to 9 wt.%) to evaluate the effect of ultrasonication techniques (bath vs. probe) on aggregate size. Probe-sonicated dispersions showed a more narrow monodispersed and unimodal aggregate size distribution with a primary average aggregate size of 255 nm. In contrast, bath-sonicated dispersions exhibited a moderately polydispersed, trimodal distribution with modes centered at 90 nm, 295 nm, and 5.6 μm. Non-Newtonian rheological parameters such as yield stress, complex viscosity, storage, and loss moduli were higher for the probe-sonicated CS-G-TiO2 composite ink than for the bath-sonicated CS-G-TiO2 composite ink. This increase is likely attributed to enhanced particle interactions, which allow for greater CS adsorption. These findings offer valuable insights into optimizing formulations for desired rheological properties in DIW printing. The results enable the direct ink writing of intricate geometries with high surface areas and less shape distortion, providing significant insights into processing similar multi-component slurry-based composite inks for DIW. / Master of Science / Researchers are exploring new ways to remove harmful toxins from waterbodies using 3D printing technology. By employing a specialized additive manufacturing (AM) printing process called direct ink write (DIW) and a composite ink (CS-G-TiO2) composed of chitosan (CS), graphene (G), and titanium dioxide (TiO2), it is possible to create parts with a tailored internal microstructure that allows for greater surface area and enhanced particle-particle adsorption kinetics. However, challenges remain with DIW of particle-filled systems, particularly regarding nozzle clogging. This assessment focuses on how the size of aggregates in G-TiO2 dispersions affects printability and the rheological behavior of the CS-G-TiO2 composite inks. To address these issues, different ultrasonication techniques and their effects on aggregate size were investigated, as well as the shear-thinning and yield stress behavior of the inks. These findings could be further analyzed to understand the underlying mechanism in particle aggregation and optimize the formulation for desired rheological properties for direct ink write (DIW) printing.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/120867 |
| Date | 06 August 2024 |
| Creators | Alidu, Mariama |
| Contributors | Chemical Engineering, Bortner, Michael J., Martin, Stephen Michael, Tallon Galdeano, Carolina |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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