Direct Ink Writing of Epoxy-Based Composites: From Structural Fabrication to the Design of Controlled Printability and Cure

Abstract: Direct ink writing (DIW) of thermoset composites offers a powerful route for fabricating complex, high-performance structures; however, it is fundamentally limited by the interplay between printability, curing behavior, and final material performance. This work addresses these challenges by developing a systematic framework to design and control epoxy-based composite inks.

To establish structural feasibility, a hybrid manufacturing approach was first developed by combining DIW-printed honeycomb cores with carbon fiber reinforced polymer face sheets. This demonstrated the potential for creating lightweight sandwich structures, while also revealing key limitations in processing window and interfacial performance that motivated further material development.

To address these limitations, formulation strategies were then explored to improve printability without sacrificing performance. By tailoring filler networks using silica nanoparticles and carbon-based reinforcements, this work establishes how network architecture governs rheological behavior and ultimately controls extrusion stability and geometric fidelity during printing.

Finally, to further advance process control, a predictive cure kinetics framework was developed to evaluate near-infrared (NIR)-assisted curing. This approach links thermal response to degree of cure, providing a pathway toward controlled, in situ curing during printing.

Overall, this dissertation demonstrates how understanding and engineering the relationship between material structure, processing behavior, and curing enables the design of printable thermoset composites with improved performance and manufacturability.