Effect of 3D printing process parameters on the mechanical properties of silica/polyethyleneimine composites using direct‐ink writing

Abstract Direct‐ink writing (DIW) 3D printing technology has the advantages of simple process and high efficiency, and enables the molding of materials at room temperature. These characteristics make DIW technology widely applicable in the field of monolithic molding. In this study, a composite slurry of SiO 2 and polyethyleneimine (PEI) was molded using direct‐ink writing 3D printing technology. Fourier transform infrared spectroscopy, x‐ray diffraction, and thermogravimetric were used to analyze the structure and thermal characteristics of the composites. Additionally, the study investigated the extrusion flow under different pressures and the impact of ink formula on their rheological behavior and printability, along with an examination of the effects of printing parameters on the mechanical properties of the monolithic structures. The results indicate that the tensile strength of the dumbbell‐shaped specimen increases with greater sample density and reduced nozzle diameter. At a filling angle of ±45°, the void rate is minimal, and the tensile strength reaches a maximum of 1.73 MPa. The tensile strength is maximum when the nozzle diameter is 0.8 mm. On the other hand, the compressive strength of the specimen is directly proportional to the layer thickness – it increases upon reducing the layer thickness. When the layer thickness is 0.3 mm, the compressive strength reaches 0.13 MPa. This study provides insights into direct‐ink writing 3D printing technology and its relationship with the mechanical properties of SiO 2 /PEI composites monolithic structures. Highlights Self‐standing fumed silica/polyethyleneimine (PEI) composite monoliths were shaped by Direct Ink Writing (DIW) technology. The impact of composite slurry composition on their rheological behavior and printability was examined. Printing parameters effects on mechanical properties of monolithic structures assessed. Significant insights into the relationship between extrusion pressure and forming structure of the composite monoliths are revealed by our research, thereby contributing to the optimization of printing processes.