Microcapsule based self-healing for 3D printed polymer composites
Type of DegreeMaster's Thesis
Polymer and Fiber Engineering
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Polymer composites are widely used in many industries due to their superior properties. Many of these composites are 3D printed to allow for greater customization and control over the properties. However, the replacement of damaged/ faulty composites is very costly and time consuming. Therefore, there is a need for self-healing composites which can recover its properties even after a damage event. Self-healing materials have gained increased traction among the research community, over the years, because of their inherent ability to detect and autonomously heal any damage to the material system. Various attempts have been made to develop increasingly efficient self-healing systems and their eventual integration in polymers at a large scale. There are three main approaches for achieving self-healing properties in a material system: microcapsule- based healing systems, vascular-based healing systems, and intrinsic healing systems. This research is focused on the preparation of a self-healing system with microcapsules as their healing agents. High impact polystyrene (HIPS) and Polylactic acid (PLA), which are two materials that exhibit excellent 3D printing properties are to be used as the bulk polymer in these systems. The polymer samples were made using a combination of solvent casting and melt casting techniques. Comparative tests of samples with and without the self-healing microcapsules were conducted to determine the effect of the microcapsules on the virgin and self-healing properties of HIPS and PLA. Characterization included differential scanning calorimetry, thermogravimetric analysis, optical microscopy, scanning electron microscopy, dynamic mechanical analysis, flexure as well as fracture tests to evaluate healing efficiency. ii Acknowledgments Throughout the writing of this thesis, I have received a great deal of support and assistance. I would first like to thank my supervisor, Dr. Asha-Dee Celestine, whose expertise was invaluable in the formulating of the research topic and methodology in particular. I would particularly like to single out my Head of Department, Dr. Maria Auad. Dr. Auad, I want to thank you for the opportunity I was given to conduct my research and further my dissertation with Dr. Celestine. I would also like to thank Dr. Bryan Beckingham, for his valuable guidance throughout this project. You provided me with the tools and the lab that I needed to successfully complete my dissertation. Special thanks to Dr. Uday Vaidya and Dr. Nitilaksh Hiremat at the University of Tennessee- Knoxville for performing DMA experiments. In addition, I would like to thank my parents and my significant other, for their wise counsel and sympathetic ear. You are always there for me. Finally, there are my friends, who were of great support in deliberating over our problems and findings, as well as providing a happy distraction to rest my mind outside of my research.